Fast Radio Bursts are a new and mysterious astrophysical phenomenon in which short (few ms) radio bursts appear randomly in the sky. FRBs are thought to be extragalactic due to their dispersion measures that are far higher than the maximum amount available in our Milky Way. With FRB event rates of ~1000 /sky/day, they raise an interesting puzzle regarding their origin, which lie at cosmological distances. Radio pulsars are rapidly rotating, highly magnetized neutron stars. As compact objects, they embody physical extremes of gravity, density and magnetic field. Thanks to their amazing clock-like properties, radio pulsars can be used as cosmic laboratories for a variety of experiments ranging from tests of relativistic gravity to studies of the interstellar medium.

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a new radio telescope recently built in Penticton, BC. CHIME's great sensitivity and large field-of-view (250 sq deg) enable the detection of many FRBs per day — in contrast to the fewer than 2 dozen discovered since 2007. CHIME is also an excellent pulsar observatory, able to detect hundreds of pulsars every day and enabling novel experiments using these high cadence observations.

Here are proposed several possible research projects involving data from CHIME. Possibilities include improving FRB characterization, studying repeating FRBs, localizing FRBs, monitoring radio pulsars, and developing software tools to search for pulsars with CHIME.

The student, who should have experience and familiarity with programming in the Linux environment, will be given astrophysical data sets from CHIME to first familiarize themselves with source properties. Then, depending on exact interest, will analyze existing data obtained in order to understand FRBs or the radio pulsar population, or help develop and test new algorithms for our new pulsar searching pipeline.

For more information contact: Victoria Kaspi (vkaspi at physics dot mcgill dot ca).

Posted on 2023/01/12

This project will focus on the development of a flexible drone-based calibrator that will be used for characterizing radio astronomy instruments. Many radio astronomy experiments employ stationary telescopes (dishes or antennas) that are sited in remote locations. One of the most important aspects of radio telescope characterization is the measurement of the spatial response on the sky, or the “beam pattern.” Because stationary telescopes are unable to actively repoint and scan over celestial sources, the only way to obtain complete beam pattern information is to move a source relative to the telescope, scanning the full field of view. One solution to this problem is to use a drone that carries a transmitting source and antenna. By developing multiple transmitters and antennas, this calibration platform can service radio astronomy experiments operating over a wide range of frequencies.

The student who takes on this project will have the opportunity to work on a variety of tasks related to the development of drone-based calibrator. Possible areas of work include refining the construction of the custom-built drone (e.g., testing new flight controllers, implementing differential GPS), designing new antennas/transmitters for low-frequency operation, developing software tools for analyzing drone flight data, and participating in drone test flight campaigns both locally and at field sites (e.g., Uapishka Station and DRAO).

For more information contact: Cynthia Chiang (chiang at physics dot mcgill dot ca).

Posted on 2023/01/16

Measurements of the radio sky at ~100 MHz and below have the potential to open a new observational window in the universe's history. At the lowest frequencies (tens of MHz), future observations may allow us to one day probe the cosmic “dark ages,&rqduo; an epoch that is unexplored to date. Measurements at these frequencies are extremely challenging because of radio-frequency interference and ionospheric effects. The state of the art among ground-based measurements dates from the 1960s, when Grote Reber caught brief glimpses of the ~2 MHz sky at low resolution. The Array of Long Baseline Antennas for Taking Radio Observations from the Seventy-ninth parallel (ALBATROS) is a new experiment that aims to map the low-frequency sky using an array of autonomous antenna stations. These antenna stations will observe independently, over long baselines, and will be interferometrically combined offline. One array will be installed at the McGill Arctic Research Station on Axel Heiberg Island, a location that is exceptionally radio-quiet and has reduced ionospheric interference relative to lower-latitude sites.

The student who takes on this project will develop the hardware and/or electronics that are needed for the autonomous antenna stations. Possible areas of work include investigating new antenna designs, developing and testing calibration electronics, integration of the readout electronics with Starlink for remote communications, RFI qualification of the fuel cell system that provides power for year-long antenna operation, and field testing the antenna stations at sites within driving distance, e.g. Uapishka Station. In addition to developing a broad spectrum of experimental skills, the student will also gain exposure to working within a multi-institution collaborative setting.

For more information contact: Cynthia Chiang (chiang at physics dot mcgill dot ca).

Posted on 2023/01/16

Black hole physics provides a powerful window onto some of the deepest and most perplexing questions in quantum field theory and quantum gravity. This can be made precise using the holographic correspondence, which relates theories of quantum gravity to conformal field theories (CFTs) in one less dimension. These CFTs are similar to the field theories which describe the fundamental forces of particle physics, as well as to those which describe important statistical and condensed matter systems at criticality. In studying this correspondence, we have made a surprising discovery: it appears that the simplest theories of gravity are related to field theories where the coupling constants are essentially random variables, much like in a spin glass or other disordered system. This leads to a remarkable relationship between the microscopic physics of black holes and the study of “random&rqduo; conformal field theories. A key role is played by wormholes – geometries which connect two distant regions of space-time, and are the geometric avatars of this randomness. Here we propose a project where a student investigates these families of conformal field theories, and their relationship with simple theories of gravity that contain wormholes.

A student who takes on this project will investigate methods which allow one to average over spaces of conformal field theories and compare the result to expectations based on semi-classical gravitational path integrals. The student should have some familiarity with general relativity and be prepared to invest some time in learning related mathematical techniques in strongly coupled quantum field theory. This is a theory project which may include some numerical component.

For more information contact: Alex Maloney (maloney at physics dot mcgill dot ca).

Posted on 2023/01/21

In this collaborative project between the Reisner and Grutter groups, the USRA student will help develop a new technique for making precisely positioned sub 5 nm nanopores. The successful ndemonstration of nanopore sequencing via engineered protein pores has created considerable industrial interest in nanopore based technologies. The next research frontier in nanopore physics is the development of solid-state nanopore devices, which admit of more scalable fabrication processes and will potentially have higher resolution, decreasing the high sequencing error-rates that are currently the main drawback in nanopore sequencing. We have developed a new approach for fabrication of sub 5 nm pores via local dielectric breakdown induced by a conductive AFM tip across a ~10nm nitride membrane. In our approach, a conductive AFM tip is brought into contact with a nitride membrane sitting on top of an electrolyte reservoir. Application of a voltage pulse leads within seconds to formation of a nanoscale pore that can be detected by a subsequent AFM scan. This method combines the ease of classic dielectric breakdown with the nanoscale pore positioning capability of high energy particle milling techniques such as TEM and FIB.

The student will learn all aspects of the pore-making and characterization process and enable interfacing of pores with chips containing nanochannels. In particular, the student will learn how to fabricate pores via AFM, characterize these devices using IV measurements performed with a patch-clamp amplifier, and then either explore fabrication physics in greater depth or use this approach to fabricate nanofluidic devices containing two closely separated nano pores for controlled translocation. Note that the Grutter and Reisner labs are next door to each other on the 4th floor of the Rutherford building; pores are fabricated in one lab and then walked over and characterized in the other, so use of facilities in both labs is clearly focused towards one project. Professor Reisner will be the primary supervisor with meetings taking place once a week; monthly meetings will take place between all projects participants, including Prof. Grutter. If pandemic conditions prevent on-site research, the student instead will perform Comsol simulations of pore formation process and ionic transport through pores.

For more information contact: Walter Reisner (reisner at physics dot mcgill dot ca).

Posted on 2022/01/31

How do multiple interacting polymers behave in confined environments? This is a fundamental problem in confined polymer physics with important implications in a range of biological systems, from chromosomal segregation and plasmid distribution in dividing bacteria to chromatin organization. The Reisner group is developing nanofluidic assays to explore how multiple polymer molecules behave in confined environments. These in vitro confinement models, where all parameters can be directly controlled, will enable testing of whether simple polymer theories can explain DNA organization in biological systems. In detail, nanofluidics will be used to confine multiple chains, using either hydrodynamic flow to compress multiple molecules against slit barriers in nanochannels, or pneumatic actuated lids to trap molecules in nanocavity structures. Differential staining of the chains will be used to independently assess the conformation of each chain, determine the degree of partitioning/mixing and assess coupled diffusion of the chain center-of-mass positions. Measurements will be performed as a function of cavity dimension, salt concentration, degree of molecular crowding, polymer topology, chain number and chain size.

The student will learn how to perform confined polymer experiments on Reisner lab fluorescence microscopy platforms. This training includes chain staining protocols, nanofluidic device and microscope operation. The student will then develop automated analysis routines in either Matlab or python to extract key qualities from the videomicroscopy data. The student will be supervised in the lab by a PhD student and meet with Prof. Reisner on a weekly basis.

For more information contact: Walter Reisner (reisner at physics dot mcgill dot ca).

Posted on 2022/01/31

The merger of a binary system of two neutron stars or a neutron star and black hole produces gravitational waves: ripples in the fabric of spacetime itself. These events also shine across the electromagnetic spectrum. In particular, these mergers eject large numbers of free neutrons, which then combine to produce radioactive isotopes of the heavy elements, including silver, gold, lead, and uranium; these freshly-synthesized isotopes then decay and these decay products thermalize to power an ultraviolet/visible/infrared transient source known as a kilonova. By establishing the association between a kilonova and gravitational waves---as was done for the first time (and only time to date) in 2017 for the event GW170187---we can study the nucleosynthesis of the heavy elements, the neutron star equation of state, and fundamental cosmology. However, these electromagnetic signatures are extremely short-lived. Electromagnetic follow-up of gravitational wave sources must be fast and efficient. To this end, we have developed a data pipeline for rapid electromagnetic follow-up with the MegaCam and/or Wide-field Infra-Red Camera (WIRCam) on the Canada-France-Hawaii Telescope. This pipeline processes the wide field-of-view images taken by these instruments to search for transient kilonovae. However, many improvements must be made and segments of this pipeline must be automated in preparation for the gravitational wave observatories to resume operation in Spring/Summer 2023.

Student(s) would be tasked with improving and automating segments of the CFHT MegaCam/WIRCam pipeline in preparation for the next gravitational wave observatories’ observing run. In particular, a student(s) would be tasked with automating the process of taking the difference between two images to look for new transient sources (image subtraction), assessing the possibility that a transient is real or bogus using machine learning (classification), and stringing together multiple nights of observations (light curve generation) so that these components of the pipeline can proceed without extensive human intervention. This work is crucial for handling the large volumes of data expected from the next gravitational wave observatories’ observing run. This project will involve extensive programming, in particular on high-performance computing clusters. Student(s) will gain experience with machine learning for classification of images. If time permits, student(s) may also work on improving the performance of the classification algorithm.

The student will perform this work in collaboration with a supervisor and progress will be monitored through weekly one-on-one meetings. Additionally, the student will have the opportunity to interact with the research group via weekly group meetings and other summer training activities.

For more information contact: Daryl Haggard (dhaggard at physics dot mcgill dot ca).

Posted on 2023/01/31

Stellar-mass black hole X-ray binaries (BHXBs) in our own Galaxy provide ideal laboratories to study the accretion process, one of the fundamental physical processes that forms the building blocks of our Universe. BHXBs emit radiation across multiple wavelengths. The source of this emission is well known in some wavebands and less established in others. Radio emission is attributed to the synchrotron process occurring in collimated outflows, referred to as relativistic jets, which carry matter/energy away from the binary system. While X-rays can originate via: direct thermal black-body emission from the hot inner accretion disc close to the black hole, via comptonization occurring in gas existing above/around the accretion disc, or at the base of the relativistic jet, where material is launched away from the system. The Ultraviolet (UV), Optical, and Infrared (IR) emission is among the most complex. It may come from multiple sources, including: direct or reprocessed (X-rays emitted close to the black hole illuminate the gas) photons from the accretion disc, the companion star, and even parts of the jet outflows.

One can disentangle the many complex emission mechanism present in BHXBs by investigating the relationship between the emission observed at UV/Optical and X-ray wavelengths during their bright outburst periods. This project will use the vast archive available from the space-based Neil Gehrels Swift Observatory, the WATCHDOG database (Tetarenko+2016), and technique developed by Russell+2006, to build UVO/X-ray correlations for the BHXB population of our own Galaxy. By fitting physically motivated models to these correlations, one can compute the fraction of emission that each component in the binary system contributes throughout an outburst cycle.

In order to accomplish the project goals, the student will learn: (i) how to download and reduce X-ray, UV, and Optical observations from the instruments aboard the Neil Gehrels Observatory using the HeaSoft software package,(ii) X-ray data analysis techniques: extracting temporal and spectral information from observations, and fitting physically motivated numerical models to such data products, (iii) UV and Optical data analysis techniques: photometry, and (iv) Python coding and Bayesian statistical methods used to fit analytical models to observational data, and create scientifically useful plots.

The student will perform this work in collaboration with a supervisor and progress will be monitored through weekly one-on-one meetings. Additionally, the student will have the opportunity to interact with the research group via weekly group meetings and other summer training activities.

For more information contact: Daryl Haggard (dhaggard at physics dot mcgill dot ca).

Posted on 2023/01/31

A fraction of nearby galaxies (elliptical galaxies) are gas rich but with scarce star formation. It is crucial to constrain their star formation rates in a spatially resolved manner, to figure out where this so-called star formation quenching originates. H-alpha emission lines, excited by young and massive stars, are a good tracer of star formation rate. We have observational data for a few elliptical galaxies from the SITELLE instrument at CFHT and the MUSE instrument on the VLT. The challenging of this project lies in accurately measuring faint H-alpha lines with contamination from old stars and background active galactic nuclei. Several tools are already available for this analysis and the student can compare their work to existing, preliminary results, but it will be their task to find a systematic method to accurately measure star formation rates in elliptical galaxies.

The student will explore cutting-edge tools and build a pipeline that can convert raw observational data cubes into accurate measurements of star formation rate. They will become expert in working with complex data from the SITELLE optical imaging Fourier transform spectrometer on the Canada France Hawaii Telescope (CFHT) and the MUSE integral field spectrograph on the Very Large Telescope (VLT). Their initial task will be to compare traditional spectral extraction methods to more novel techniques that use machine learning. They will use the Python coding language and some background in astronomy and/or astrophysics will be useful. The student will likely lead a manuscript on the discovery, and will be part of other manuscripts that use these results.

The student will perform this work in collaboration with a supervisor and progress will be monitored through weekly one-on-one meetings. Additionally, the student will have the opportunity to interact with the research group via weekly group meetings and other summer training activities.

For more information contact: Daryl Haggard (dhaggard at physics dot mcgill dot ca).

Posted on 2023/01/31

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a radio interferometer in British Columbia which combines the large field of view of small telescopes with the sensitivity of larger instruments. This combination makes CHIME a powerful tool for detecting transient or variable signals from the sky. This research project will focus on a particular population of variable sources known as blazars. Blazars are a special class of active galactic nuclei (AGN), characterized by having relativistic jets that happen to be pointed in the direction of Earth. This serendipitous viewing geometry make blazars ideal laboratories for studying AGN and their jets. In particular, regular monitoring of blazars at radio wavelengths can provide us with an observational handle on a range of phenomena, including binary interactions, accretion and jet physics, and the associated production of high energy neutrinos and gamma rays.

The student will develop a software pipeline for extracting daily observations of Northern Hemisphere blazars from the CHIME data archive, and for detecting specific variability signatures in the resulting light curves. They will also develop automated versions of these pipelines to reduce the latency for public release of future data

For more information contact: Dalas Wulf (dallas dot wulf at mcgill dot ca).

Posted on 2023/02/02

Gated semiconductor solid-state spin qubits are a promising candidate for the scalable implementation of quantum technologies because of their long coherence times and nanometer-scale dimensions. We are using a computational modeling method called Quantum Technology Computer Aided Design (QTCAD)[1] to predict properties of solid-state spin-qubits. QTCAD treats Coulomb interactions between electrons confined within the quantum-dot by exact diagonalization. It has a transport module which calculates current flowing through the quantum-dot under external potentials. However, the effect of an applied gate potential is so far approximately treated by rigidly shifting the quantum-dot energy levels. This leads to predictions of qubit property less quantitative compared with experimental data. Indeed, in experimental devices, the ratio of capacitances between contacts and the quantum dot give rise to a finite "lever arm" of the applied gate potential. This level arm should be calculated accurately to obtain quantitative results.

The research in this project is to determine the level arm and gate capacitance of quantum dots routinely fabricated by the semiconductor industry[2], based on QTCAD. If successful, realistic charge stability diagram calculations can be carried out for the solid-state devices. The research work includes (but may not be limited to) the following:

1. Leveraging the Poisson and Schrödinger-Poisson[3] solvers available in QTCAD to selfconsistently determine gate potential profile in various gated quantum dot devices fabricated by semiconductor industry, including those based on the three-dimensional FinFET[4] and/or planar FD-SOI[2] transistors.
2. From the quantitative potential profile (level arm), determine gating efficiency of these devices. Using the calculated gating efficiency for FinFET and FD-SOI devices, determine a proper rigid shift scaling of the gate potential.
3. rom the electrostatic potential distribution, calculate the gate capacitances of these quantum dot systems[5].
Time permitting, calculate realistic charge stability diagrams of the solid-state devices using the many-body solver of QTCAD, comparing to experimental data.

This work not only provides accurate calculations of quantum-dot systems, but also provides gate capacitances that is useful for large quantum-dot array simulations[6] (e.g. the orthodox theory) or in applications beyond quantum dots.

Research outcome:

1. Classical capacitance calculation (from Poisson solver). This is the primary goal.
2. Quantum capacitance calculation (from Schrödinger-Poisson). This will be nice to have.
3. Gate efficiencies of FinFET and FD-SOI quantum dots, this is another primary goal.
4. Charge stability diagrams in realistic FinFET and FD-SOI quantum dot devices, this will be nice to have.

References:
[1] https://nanoacademic.com/solutions/qtcad/.
[2] Féelix Beaudoin, Pericles Philippopoulos, Chenyi Zhou, Ioanna Kriekouki, Michel Pioro-Ladriere, Hong Guo, and Philippe Galy,, Appl. Phys. Lett. 120, 264001 (2022).
[3] Calculation of capacitance from Schrödinger-Poisson solver, Gao et al. J. Appl. Phys. 114, 164302 (2013).
[4] Andreas V. Kuhlmann, Veeresh Deshpande, Leon C. Camenzind, Dominik M. Zumbühl, and Andreas Fuhrer, Appl. Phys. Lett. 113, 122107 (2018).
[5] Calculation of the electric potential at the dot from capacitances https://lampx.tugraz.at/~hadley/ss2/set/transistor/coulombblockade.php
[6] Kalantre et al. npj Quantum Information 5, 1 (2019) ­ Supplements p. 2.

For more information contact: Hong Guo (guo at physics dot mcgill dot ca).

Posted on 2023/02/02

VERITAS is a VHE (Very High Energy: E > 100 GeV) instrument composed of an array of four 12-m telescopes, designed to detect and study VHE gamma-rays from astrophysical sources using the air Cherenkov technique. The instrument is mature (on-sky since 2007) and the collaboration has published more than 100 results; we continue to acquire data with a focus on the transient sky. The analysis software is custom-built, but the VHE field is moving towards standard, open-source, python-based packages such as gammapy. In this project the student will work with gammapy to validate past VERITAS analyses in this new package, developing new tools for gammapy as required. In parallel with this validation work, the student will participate in ongoing VERITAS analyses such as a search for Lorentz-invariant effects in astrophysical contexts, or investigation of recent VERITAS data on supermassive black holes and supernova remnants.

For more information contact: Ken Ragan (ragan at physics dot mcgill dot ca).

Posted on 2023/02/02

In nanoelectronic device physics, an important problem is to predict electron-phonon (e-p) scattering from atomistic first principles. Phonons are collective modes of atomic vibrations at finite temperature. Electrons traversing a nanoscale device are scattered by the phonons. In first principles theory and modeling methods, phonons in device materials are determined by a tedious procedure which is hard to achieve when the number of atoms are more than a few hundred. Such first principles approach is typically limited to problems of academic interest [1].

More recently, an approximate approach termed special thermal displacement (STD) [2,3,4] method has emerged to be able to calculate phonon limited physical properties, including temperature dependent conductivity, band-gap narrowing, polarons, and quantum transport. In STD, one first determines the phonon modes of the atomic lattice, followed by inverting the phonon modes into real space atomic displacements that are used to construct the STD. With STD as the effective atomic structure, a single calculation approximately but rather accurately gives the desired physical quantity (i.e. conductivity). This approach avoids the tedious calculation of the e-p scattering self-energy[1] and can therefore be applied more complicated material systems. Nevertheless, a drawback of STD is the requirement of the phonon modes which typically requires lengthy atomic calculations to obtain.

The research in this project is to exploit the possibility to construct STD by using molecular dynamics (MD) trajectories. It has been known that the two-point correlation function of atoms in MD is related to phonon density of states, STD may be constructed by MD which is easy to do. If successful, realistic and large atomic structures can be investigated for the e-p scattering effects. The research work includes (but may not be limited to) the following:

1. Develop a simple MD method to solve Newtonian dynamics of atoms under a thermostat. The force field between atoms will be handled at the classical level (i.e. Stillinger­Weber potential).
2. Calculate the MD trajectories of typical semiconductor nanostructures such as Si nanowires.
3. Investigate how to construct STD configurations from the MD trajectory. If successful, perform STD calculations to determine band-gap narrowing using density functional theory (DFT). The DFT part of the work will be collaborating with Prof. Guo's postdoctoral fellows.
4. A parallel approach is to sample the MD trajectories at different times, and use those structures to determine the physical quantity followed by a statistical averaging.

This work aims at innovating an effective approach to capture effects of e-p scattering in nanostructures having large number of atoms.

Research outcome:

1. A molecular dynamics method and code. This is the first goal.
2. Construction of STD configurations from MD trajectories. This is the second goal.
3. Calculate phonon limited physical quantities of Si nanowires.

References:
[1] N. Sergueev, D. Roubtsov, and Hong Guo, Phys. Rev. Lett. 95, 146803 (2005).
[2] M. Zacharias and F. Giustino, Phys. Rev. B. 94, 075125 (2016).
[3] M. Zacharias and F. Giustino, Physical Review Research 2, 013357 (2020).
[4] T. Gunst, T. Markussen, M. L. Palsgaard, K. Stokbro, and M. Brandbyge, Phys. Rev. B 96, 1 (2017).

For more information contact: Hong Guo (guo at physics dot mcgill dot ca).

Posted on 2023/02/03

Neptune-class planets are primarily composed of rocky and icy material but a few tens of percent of their mass is contained in hydrogen and helium accreted from the protoplanetary disk. The amount of metals (elements other than H-He) present in these H-He envelopes is a probe of the formation history of Neptunes-class planets as it depends on the rate at which these planets accrete solids and gas. This accretion rate of solids and gas in turn depends on the formation location, the solid surface density and size distribution, and the nascent envelope’s composition and opacity. In this project, we will determine how the atmospheric compositions of Neptune-class planets depend on their formation conditions and whether variations in these conditions can explain the observed diversity in the atmospheric compositions of such planets. We will also evaluate whether the observed composition of Neptune-class planets can be used to infer their formation conditions.

The student will model the interaction of solids and gas in a growing planet’s envelope to determine how metal enriched the envelope will become. They will then study how changing the formation conditions of the planet (e.g., location, solid surface density) changes the envelope composition. The student will need to become very familiar with the underlying physics that is already established in the literature. The project will strengthen the student’s background in fluid dynamics, thermodynamics, and computational modeling in astrophysics.

For more information contact: Eve Lee (eve dot lee at mcgill dot ca).

Posted on 2023/02/03

The EXO (Enriched Xenon Observatory) collaboration is searching for lepton-number violating neutrino-less double beta decays (0νββ) in Xe-136. A positive observation would require the neutrino to be its own anti-particle, i.e. the neutrino has to be a Majorana particle, and shed light on various open questions in neutrino physics. The EXO collaboration is pursuing the development of the next-generation experiment called nEXO. This advanced detector requires the development of new technologies as well as detailed knowledge of the underlying physical processes to reach a sensitivity goal to the 0νββ half-life of 1028 years.

We have been developing the Light-only Liquid Xenon (LoLX) experiment at our lab at McGill which aims to measure the emission of Cherenkov light in liquid xenon (LXe), investigate crosstalk between silicon photomultiplier devices, and deepen our understanding of light emission in LXe. These measurements will help constrain our simulation models for nEXO. LoLX may also improve event identification and suppress backgrounds by separating events where one or two electrons are emitted. This summer, we plan to perform several measurements with SiPMs installed in our upgraded LoLX cryostat. Operating this upgraded cryogenics system requires new control systems to be developed and tested. In addition, it will be required to validate our simulation model with recorded data.

Your main task will be to simulate the expected response function of SiPMs in LoLX using the ray-tracing package CHROMA (GPU-based). You will also support the operation of the cryostat, participate in data taking campaigns and compare simulation results to recorded data. You will be embedded within the local neutrino group at McGill and learn about particle physics, the use of liquid xenon as a radiation detector, and how to read cryogenic temperatures using thermocouples and RTDs

This project is aimed at undergraduate students at all levels. All you need is an interest in nuclear/particle physics and a strong willingness to learn. Programming knowledge in any language (C or Python preferred) would be beneficial but is not necessary, as we have local experts who will be happy to teach you. You will apply your knowledge of thermodynamics in a real life experiment, and take part in the operation of the upgraded LoLX cryostat.

For more information contact: Thomas Brunner (thomas dot brunner at mcgill dot ca).

Posted on 2023/02/04

Cloud chambers (see: https://en.wikipedia.org/wiki/Cloud_chamber) can be used to detect charged particle tracks from radioactive sources or from ambient cosmic rays, and are useful for visualization and outreach. They're also just really cool toys! Last summer, an undergraduate student built a cloud chamber from scratch (https://cloudchamber.physics.mcgill.ca/) using commercially available parts. This year we plan to improve the design to allow a larger active area where particles are visualized.

This project will consist of designing, building, and commissioning such a small detector, using Peltier cooling devices. The successful applicant will do some preliminary research to establish parts, materials, techniques, and approaches, and will then use design software to formalize those into specifications, drawings, and plans. The construction will be done with a combination of 3-D printing and machine-shop work (if necessary). The goal will be a working, easy-to-use table-top-sized detector, suitable for classroom and outreach demonstrations.

For more information contact: Thomas Brunner (thomas dot brunner at mcgill dot ca), Dominic Ryan (dominic at physics dot mcgill dot ca) or Ken Ragan (ragan at physics dot mcgill dot ca).

Posted on 2023/02/04

he nEXO (Enriched Xenon Observatory) collaboration is searching for lepton-number violating neutrinoless double beta decays (0νββ) in Xe-136. A positive observation would require the neutrino to be its own anti-particle, i.e. the neutrino has to be a Majorana particle, and shed light on various open questions in neutrino physics.

Silicon photomultipliers (SiPMs) have been identified as the devices to detect the vacuum-ultraviolet light for nEXO. Characterizing the large number of SiPMs used by the detector requires high throughput testing. At McGill we have developed an IV multiplexer that allows switching between pulse and DC measurements for up to 105 devices with low leakage current. Further development is needed to interface instruments to our data-acquisition system.

The student that takes on this project will develop an interface for laboratory instruments using LabView, and automate processes through our data-acquisition system. The student will be supported by an electronics engineer and a graduate student who have developed the electronics components of this project.

For more information contact: Thomas Brunner (thomas dot brunner at mcgill dot ca).

Posted on 2023/02/04

The Light only Liquid Xenon (LoLX) experiment is using an enclosure of SiPMs to study the optical characteristics of liquid xenon. Operating a detector with cryogenic liquids such as liquid xenon requires careful measurement of environmental parameters such as the liquid xenon fill level inside the cryostat. The detector geometry of LoLX prohibits conventional cryogenic level sensors, so a custom sensor is required and will be built as part of this project.

The student that takes on this project will do a literature search on methods employed by other groups and then perform calculations to demonstrate the optimal configuration for two parallel strips in a capacitive sensor for liquid xenon. Following the design of the sensor the student will assemble and test the sensor with liquid nitrogen and potentially with liquid xenon - depending on the availability of the LoLX cryostat.

For more information contact: Thomas Brunner (thomas dot brunner at mcgill dot ca).

Posted on 2023/02/04

Radio interferometers provide one of the most promising prospects for making the first detection of 21-cm emission from the intergalactic medium during Cosmic Dawn and the Epoch of Reionization, the period of the universe's history when the first stars and galaxies formed. This cosmic signal is estimated to be roughly 100,000 times fainter than radio emission from contaminating sources, so a detection of the 21-cm signal requires exquisite sensitivity. Many modern interferometers aim to achieve the necessary sensitivity by placing a large number of radio dishes together in regular arrays to act as a single “super telescope”. Unfortunately, tightly packing dishes in a regular pattern can give rise to excess correlation between dishes, possibly precluding the detection of the cosmic 21-cm signal. This excess correlation, often referred to as “mutual coupling”, is not well understood: it is difficult to isolate the effect in data, and it is computationally infeasible to study the effect through electromagnetic simulations of large arrays. A semi-analytic model describing this effect was recently developed and shows promise for understanding how mutual coupling manifests in redundant interferometers. Understanding this effect is essential for detecting the cosmic 21-cm signal, so there is great value in validating the semi-analytic model against a small set of electromagnetic simulations.

The student who takes on this project will perform an in-depth comparison of semi-analytic mutual coupling simulations against fully-coupled electromagnetic simulations. The student will learn how to analyze, compare, and visualize data from radio interferometers. This project will involve extensive Python programming, and will provide the student with ample opportunities to learn about radio interferometry in the context of 21-cm cosmology. The student will collaborate work within the Cosmic Dawn Intensity Mapping research group, engage in group meetings, and also have the opportunity to collaborate with others within the international Hydrogen Epoch of Reionization Array collaboration.

For more information contact: Adrian Liu (acliu at physics dot mcgill dot ca).

Posted on 2023/02/04

During Cosmic Dawn and the subsequent Epoch of Reionization, first-generation galaxies carved out “bubbles” of ionization around them. Studying the shapes and sizes of these bubbles will enable researchers to understand the nature of these galaxies. Low-frequency radio interferometers like the Hydrogen Epoch of Reionization Array or the Square Kilometre Array are currently being constructed with the partial goal of making images of these bubbles. Unfortunately, real-world instrumental effects complicate this effort, making these ionized regions difficult to identify. Recently, machine learning techniques have shown considerable promise when it comes to solving this problem. However, these techniques have been unable to recover the smallest bubbles. One potential way to improve on this limitation is to use catalogs of galaxies as markers for the bubbles. The goal of this project will be to test the viability of this idea via simulations.

The student will first work through a short online tutorial on machine learning and then learn to run already-written machine learning code for ionized bubble identification. They will then learn to run code to generate mock galaxy catalogs, before designing and training a new neural network that uses these catalogs to identify bubbles.

For more information contact: Adrian Liu (acliu at physics dot mcgill dot ca).

Posted on 2023/02/04

Cosmic Dawn (when first-generation stars formed) and the Epoch of Reionization (when first-generation galaxies ionized their surroundings) are periods in our Universe's history that remain poorly understood. Making sense of the observations from these complex eras often requires cosmological simulations. These simulations are computationally expensive. At heart, however, they are just extremely complicated mathematical functions that take the initial conditions of our Universe and output its state at a later time. A particularly desirable property for these functions would be for it to be differentiable. Unfortunately, this is not the case for 21cmFAST, a state-of-the-art simulation package for Cosmic Dawn and reionization. The goal of this project is to explore the possibility of making 21cmFAST differentiable.

The student will first learn how to run 21cmFAST and master the basic theory behind the simulation. They will then write their own reduced version of the code before invoking various approximations that will make the simulation differentiable. If time permits, there will be an opportunity to explore applications of differentiable cosmological simulations.

For more information contact: Adrian Liu (acliu at physics dot mcgill dot ca).

Posted on 2023/02/04

VERITAS is a VHE (Very High Energy: E > 100 GeV) instrument composed of an array of four 12-m telescopes, designed to detect and study VHE gamma-rays from astrophysical sources using the air Cherenkov technique. The instrument is mature (on-sky since 2007) and the collaboration has published more than 100 results; we continue to acquire data with a focus on the transient sky. The analysis software is custom-built, but the VHE field is moving towards standard, open-source, python-based packages such as gammapy. In this project the student will work with packages such as scikit-learn to adapt machine learning tools to VERITAS analyses. Examples could include optimization of gamma-ray/hadron selection criteria, improvement of low-energy photon acceptance, and improvement of energy and directional reconstruction.

For more information contact: Ken Ragan (ragan at physics dot mcgill dot ca).

Posted on 2023/02/06

Knowledge of exoplanets' interior structures and compositions provide a fundamental insight into their formation and evolution. Unfortunately, the interiors of super earths and sub-Neptunes, the most common types of exoplanet, are poorly constrained by current data. In this project, our goal is to investigate a new way to probe the deep interior of these enigmatic planets. We will leverage the fact that the geometric shape of a planet can be deformed by rotation and/or tidal interaction with their host star, and that this deformation depends on the planetary composition and structure. Our mission is to calculate how their tidally or rotationally-distorted shape changes subject to different assumptions about their chemical constituents and structure. Specifically, we will focus on 4 models of planetary interior structure, and determine whether we can differentiate between them observationally. We will probe planets comprised of a) a hydrogen atmosphere overlying a magma core (the most common assumption in the field), b) a thin hydrogen atmosphere overlying a hydrogen-magma mixture, c) a water vapor atmosphere overlying a magma core, and d) a thin water vapor atmosphere overlying a water-magma mixture. The rheological properties of these mixtures -- their viscosities and bulk moduli -- differ significantly. This suggests that the shapes of our planet models should also differ significantly, potentially giving us new constraints on the formation and evolution of these bodies.

The student will be responsible for fitting analytical scalings to the equations of state for water, hydrogen, and magma mixtures that we have already collected. These scalings will be used in a simple analytic model of the geometric distortion of the planet. The student will then compute order of magnitude estimates of how the shapes will change with different compositions. The student will also help develop a computer code that incorporates the full, realistic equations of state in computing the equilibrium shape.

For more information contact: Eve Lee (eve dot lee at mcgill dot ca).

Posted on 2023/02/06

Dark Matter (DM) accounts for 80% of the energy density of the universe. Even so its microphysical properties remain elusive. Although DM is assumed to be strictly stable at cosmological timescales, many viable DM candidates are metastable and can decay or be de-excited, leading to the production of high-energy Standard Model (SM) particles. If this decay/de-excitation happens at late times inside galaxies, it can dump energy into the interstellar/circumgalactic medium and heat/ionize clouds of neutral gas. In this project, we will first identify metastable DM states that can also have a consistent thermal history, and then will study the imprint their energy injection leaves in galaxies.

In this project, the student will learn about metastable DM candidates, will write code to numerically study the evolution of the DM density in the early universe and will perform estimates of the observable effects of various metastable DM candidates in galactic environments. Through this project, the student will develop an understanding of various parts of theoretical DM research from both a particle and astro perspective. The student should have familiarity with quantum mechanical scattering, and should be prepared to invest some time in learning about the interstellar/circumgalactic medium.

For more information contact: Katelin Schutz (katelin dot schutz at mcgill dot ca).

Posted on 2023/02/06

Dark photons are hypothetical particles that generically arise in extensions of the Standard Model (SM) with additional U(1) gauge symmetries and have been proposed as a possible explanation for dark matter. No symmetry of nature prevents such a dark photon to mix at some level with the SM photon. This is even true if the dark photon is massive, and there are many analogies that can be drawn with neutrino oscillation in the SM. In this project, we will quantify the possibility of converting dark photon dark matter to photons at an observable level in neutron star magnetospheres, where multiple contributions to the photon’s effective potential can enhance the mixing due to resonance/level crossing.The results of the project may have implications for our understanding of dark matter and its relationship to neutron stars, as well as for the design of future experiments to detect dark photons.

The student who takes on this project will calculate flux of photons (converted from dark photon dark matter) from neutron star magnetospheres and quantify the possibility of observing the resulting spectral line with current or future telescopes. They will study the mathematical framework of dark photon to photon oscillations (very much like the neutrino flavour oscillations) in the presence of strong magnetic fields and plasmas. Hence a familiarity with advanced quantum mechanics (like time-dependent perturbation theory, adiabatic theorem/Landau-Zener, etc.) would be desirable. This is mostly a theoretical project with some numerical component. The student might have to do some coding and thus some familiarity with Mathematica and/or Python would be helpful.

For more information contact: Katelin Schutz (katelin dot schutz at mcgill dot ca).

Posted on 2023/02/06

The Event Horizon Telescope image of the photon ring around M87* captivated the world, and this achievement was named Breakthrough of the year by Science Magazine in 2019. This black hole weights billions of solar masses and lives in the centre of a galaxy, making its photon ring large and bright, which helps to overcome the great distance to the M87 galaxy making the image smaller and fainter. What if the same thing was happening on a much smaller scale around isolated primordial black holes in the solar neighbourhood? In this project, we will explore the possibility that light from bright astrophysical sources like supernovae gets stuck in nearby primordial black hole photon rings, with some light coming to us a long time after the light from the supernova passed us in an apparent “black hole echo.

The student working on this project will perform estimates of the probability for photons to be stuck in photon rings or to be on parabolic orbits around primordial black holes. Given these estimates, the student will determine the prospects of observing such photon rings with existing or future telescopes. The student working on this project should have some knowledge of general relativity at the level of Schutz (no relation to the PI, believe me I’ve asked) or Carroll. Knowledge of orbital mechanics in non-Keplerian potentials will also be useful.

For more information contact: Katelin Schutz (katelin dot schutz at mcgill dot ca).

Posted on 2023/02/06

Optical metasurfaces composed of a layer of sub-wavelength nanostructures have been proven a highly powerful and versatile platform for manipulating both classical and quantum states of light [1]. Central to designing metasurfaces is their numerical simulation. However, conventional simulation methods typically suffer from too high computational costs, restricting the possibilities of basing optimizations on the simulation of the entire structure. Recent progresses in efficient simulation methods provide new opportunities in metasurface design. One remarkable recent approach, the so-called augmented partial factorization method [2], avoids solving Maxwell's equations on every element of the discretization basis set and directly computes the information of interest, which is a generalized scattering matrix given any list of input source profiles and any list of output projection profiles. While current proof-of-principles are based on 1D and 2D structures, bringing such a new simulation into practical metasurface designs would require the implementation of augmented partial factorization simulation in 3D and combining it with optimization methods. This project aims to establish an efficient 3D design code for metasurfaces using augmented partial factorization.

The student will (i) learn the basic principles of the augmented partial factorization simulation by debugging the example codes for 1D and 2D structures, (ii) develop a code for simulating 3D metasurfaces, and (iii) combine the 3D code with an optimization method to design an example metasurface for photonic state transformation.

[1] K. Wang, M. Chekhova, and Y. Kivshar, Metasurfaces for Quantum Technologies, Physics Today 75, 38 (2022).
[2] H.-C. Lin, Z. Wang, and C. W. Hsu, Fast multi-source nanophotonic simulations using augmented partial factorization, Nature Computational Science 2, 815 (2022).

For more information contact: Kai Wang (k dot wang at mcgill dot ca).

Posted on 2023/02/06

Quantum state tomography is an essential task in nearly all applications of quantum optics. In the continuous-variable picture, a quantum state can be described by a Wigner quasi-probability function in phase space. While conventionally, Wigner function tomography can be done through homodyne detection that uses the interference of the unknown quantum state with a local oscillator, very recent experimental efforts have reported the direct measurement of Wigner functions using a phase-sensitive optical parametric amplifier in a nonlinear crystal [arXiv:2207.10030]. This project aims to experimentally establish a homodyne-based Wigner function tomography setup and theoretically explore direct tomography approaches.

The student will (i) learn the basics of Wigner function tomography, (ii) experimentally build a setup that performs homodyne tomography to a laser in the telecommunication wavelength, (iii) design an optical setup that can perform direct Wigner function tomography based on optical parametric amplifiers.

For more information contact: Kai Wang (k dot wang at mcgill dot ca).

Posted on 2023/02/06

The nature of matter in the universe as well as interacions between elementary particles hold many fundamental mysteries. The study of high energy proton-proton collisions produced in a controlled laboratory environment is an ideal approach to attemp to shed light on these mysteries.

The ATLAS detector, located at the CERN laboratory in Switzerland, is designed to record the results of the highest energy proton-proton collisions in the world. The detector is undergoing major upgrades in order to be ready to record the results of proton-proton collisions at the future High-Luminosity Large Hadron Collider (LHC), scheduled to begin operation in 2029. One of these upgrades consists in replacing the entire electronic readout of the Liquid Argon Calorimeter detector, a sub-system responsible for precisely measuring the energy of electrons/photons produced in proton-proton collisions.

The overarching goal of the summer project is to develop digital filters, based on machine learning techniques, that are optimized for the real-time reconstruction of energy deposited in the ATLAS liquid argon calorimeter system, and to study their performance. Specifically, (1) the student will learn how to use existing software tools for simulating the electronic response of the future calorimetner readout system. (2) The student will explore different possible machine learning models guided by the feasibility and ease of their implementation in hardware description language on the future customed digital signal processing system currently being designed. Considerations include, e.g. the number of parameters and type of mathematical operations required by each model. (3) The performance of the most promising machine learning model(s) will be studied under different experimental conditions.

The student will carry-out leading-edge research and develop computer programming skills, learn about the construction of different Machine Learning models and their optimization, learn about general concepts of particle detector instrumentation, different concepts related to analogue and digital electronics, and develop some knowledge of Field-Programmable Gate Arrays (FPGAs). Through the international context of their research work, the student will be exposed to an international network of scientists, providing them with a unique opportunity to develop their communication and collaborative skills.

Research activities will take place in person at McGill University. The student will perform this work in collaboration with a supervisor. The student's progress will be monitored through weekly meetings. Additionally, the student will regularly interact with other members of the McGill ATLAS research group (research associates, engineer and graduate student), as well as collaborate with colleagues at other institutes in Canada and internationally.

The student is required to be resourceful, curious and have a strong desire to learn. Knowledge and experience with computers (unix-based OS, shell scripts, python, C++, git) is considered an asset.

For more information contact: Brigitte Vachon (brigitte dot vachon at mcgill dot ca).

Posted on 2023/02/13

The nature of matter in the universe as well as interacions between elementary particles hold many fundamental mysteries. The study of high energy proton-proton collisions produced in a controlled laboratory environment is an ideal approach to attemp to shed light on these mysteries.

The ATLAS detector, located at the CERN laboratory in Switzerland, is designed to record the results of the highest energy proton-proton collisions in the world. The detector is undergoing major upgrades in order to be ready to record the results of proton-proton collisions at the future High-Luminosity Large Hadron Collider (LHC), scheduled to begin operation in 2029. One of these upgrades consists in replacing the entire electronic readout of the Liquid Argon Calorimeter detector, a sub-system responsible for precisely measuring the energy of electrons/photons produced in proton-proton collisions. As part of the new electronic readout, the off-detector signal processor system will be responsible for processing, in real-time, the incoming digitized data stream of 345 Tbps from the calorimeter. This off-detector system will consist in ~ 400 monolithic custom-designed blades hosting two high-performance Field-Programmable Gate Arrays (FPGA) processing units.

The goal of the summer project is to contribute to the design and construction of a test infrastructure at McGill for the quality assessment of these complex, customed digital electronics cards. The student will (1) help install, commission and operate differents parts of the test infrastructure (2) help develop operational and monitoring scripts, software and databases for the interpretation of the various electronics tests being considered.

The student will carry-out leading-edge research and acquire knowledge in the general areas of detector instrumentation, state-of-the-art electronics, computer programming, develop problem solving skills, acquire hands-on laboratory experience, and develop knowledge and experience with the use of FPGAs. Through the international context of their research work, the student will be exposed to an international network of scientists, providing them with a unique opportunity to develop communication and collaborative skills.

Research activities will take place in person at McGill University. The student will perform this work in collaboration with a supervisor. The student's progress will be monitored through weekly meetings. Additionally, the student will regularly interact with other members of the McGill ATLAS research group (research associates, engineer and graduate student), as well as collaborate with colleagues at other institutes in Canada and internationally.

The student is required to be resourceful, curious and have a strong desire to learn. Knowledge and experience with computers (unix-based OS, shell scripts, python, C++, git) is considered an asset.

Note: For IPP Summer Student Fellowship recipients, this project is particularly well-suited because it will allow you to pursue this project during your stay at CERN under the supervision of McGill group members working at the CERN-based electronic test infrastructure currently being developed.

For more information contact: Brigitte Vachon (brigitte dot vachon at mcgill dot ca).

Posted on 2023/02/13

The nature of matter in the universe as well as interacions between elementary particles hold many fundamental mysteries. The study of high energy proton-proton collisions produced in a controlled laboratory environment is an ideal approach to attemp to shed light on these mysteries.

The student will participate in the development of an analysis framework for the interpretation of measurements performed using proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider (LHC).

Specifically, the student will help develop the statistical methods and an analysis framework for the combination and interpretation of measurements of extremelly rare physics reactions in terms of constraints on possible new physics phenomena. The student tasks will include learning about different statistical methods, as well as the writing and validation of analysis code written in C++/Python, and based on ROOT analysis libraries.

The student will carry-out leading-edge research and acquire knowledge in the general areas of data analysis and statistical interpretation of data, computer programming, develop problem solving skills, develop familiarity with general concepts and tools in experimental particle physics. Through the international context of their research work, the student will be exposed to an international network of scientists, providing them with a unique opportunity to develop communication and collaborative skills.

Research activities will take place in person at McGill University. The student will perform this work in collaboration with a supervisor. The student's progress will be monitored through weekly meetings. Additionally, the student will regularly interact with other members of the McGill ATLAS research group, as well as collaborate with colleagues at other institutes in Canada and internationally.

The student is required to be resourceful, curious and have a strong desire to learn. Knowledge and experience with computers (unix-based OS, shell scripts, python, C++, git) is considered an asset. Familiarity with complex statistical methods, or demonstrated ability to independently learn complex theoretical concepts, is also considered an asset.

For more information contact: Brigitte Vachon (brigitte dot vachon at mcgill dot ca).

Posted on 2023/02/13

The nature of matter in the universe as well as interacions between elementary particles hold many fundamental mysteries. One of these mysteries is the nature of the so-called Dark Matter in the Universe. Quantum optomechanical accelerometers are being explored as a new avenue to search for the existence of ultra-light Dark Matter.

The student will be tasked with developing software to simulate potential signals from one or several such devices. The student will study different analysis techniques and explore the sensitivity of different detector geographical configurations as function of dark matter mass and coupling.

Research activities will take place in person at McGill University. The student will perform this work in collaboration with a supervisor. The student's progress will be monitored through weekly meetings.

The student is required to be resourceful, curious and have a strong desire to learn. Knowledge and experience with computers (unix-based OS, shell scripts, python, C++, git) is considered an asset

For more information contact: Brigitte Vachon (brigitte dot vachon at mcgill dot ca).

Posted on 2023/02/13

Accurately measuring the joint spectral properties of photon pairs is crucial for various applications, such as creating high-quality heralded single-photon states and generating polarization-entangled bi-photon states for multiphoton protocols. However, current experimental methods either indirectly analyze these properties through the reversed nonlinear process of sum-frequency generation or rely on slow, reconfigurable setups that use a tunable monochromator and single-photon detectors. Recent advances in imaging-based photon pair measurements made it possible to directly achieve joint spectrum intensity (JSI) measurements through a diffractive grating in conjunction with an image sensor, enabling fast and simple characterization of such important spectral properties of correlated photon pairs.

The student working on this project will build up an experimental setup capable of generating correlated photon pairs via spontaneous parametric down-conversion (SPDC) using a periodically poled potassium titanyl phosphate (PPKTP) crystal and perform direct measurement of the joint spectral distribution of the photon pairs using a diffractive grating and an image sensor. The student will measure a variety of joint spectral distributions at different phase-matching conditions via temperature tuning. The student will work closely with an MSc student who has expertise in correlated photon pair imaging.

For more information contact: Kai Wang (k dot wang at mcgill dot ca).

Posted on 2023/02/20

The combination of machine learning and quantum computing has emerged as a promising approach for solving previously untenable problems, which holds great promise in many fields, from drug discovery to cryptography. Photons encoded in the discrete-time degree of freedom constitute a promising platform for quantum computing with the advantage of compactness and operation at room temperature [1]. However, the design of such optical-fiber-loop-based devices for quantum machine learning tasks remains lacking. Judiciously designed optical setups can potentially realize a variety of quantum machine learning algorithms, such as quantum reservoir computing in the time domain [2] and quantum self-learning machines [3].

The student working on this project will theoretically design an optical fiber-loop-based setup for quantum machine learning that is suitable for running at least one type of algorithm. After the design is achieved, the student will have a hands-on opportunity to build a simple part of the proposed fiber setup that can dynamically realize 2x2 linear transformations. The experimental task includes connecting optical fibers to construct a Mach-Zehnder interferometer, controlling electro-optic modulators inside the interferometer, and characterizing the transformations using classical laser light.

[1] B. Bartlett, A. Dutt, and S. Fan, Deterministic Photonic Quantum Computation in a Synthetic Time Dimension, Optica 8, 1515 (2021).
[2] J. Chen, H. I. Nurdin, and N. Yamamoto, Temporal Information Processing on Noisy Quantum Computers, Phys. Rev. Appl. 14, 1 (2020).
[3] V. Lopez-Pastor and F. Marquardt, Self-Learning Machines Based on Hamiltonian Echo Backpropagation arXiv:2103.04992 (2021).

For more information contact: Kai Wang (k dot wang at mcgill dot ca).

Posted on 2023/02/20