Noncommuting charges: Bridging theory to experiment

Noncommuting conserved quantities have recently launched a subfield of quantum thermodynamics. In conventional thermodynamics, a system of interest and an environment exchange quantities—energy, particles, electric charge, etc.—that are globally conserved and are represented by Hermitian operators. These operators were implicitly assumed to commute with each other, until a few years ago. Freeing the operators to fail to commute has enabled many theoretical discoveries—about reference frames, entropy production, resource-theory models, etc. Little work has bridged these results from abstract theory to experimental reality. This work provides a methodology for building this bridge systematically: we present a prescription for constructing Hamiltonians that conserve noncommuting quantities globally while transporting the quantities locally. The Hamiltonians can couple arbitrarily many subsystems together and can be integrable or nonintegrable. Our Hamiltonians may be realized physically with superconducting qudits, with ultracold atoms, and with trapped ions.

Dissipative landau Zener transition in the weak and strong coupling limits

Landau Zener (LZ) transition is a paradigm to describe a wide range of physical phenomenon. Dissipation is inevitable in realistic devices and can affect the LZ transition probabilities. I will describe how we can model the effect of the environment depending on whether it is weakly or strongly coupled to the system. I will also present our experimental results where we found evidence of crossover from weak to strong coupling limit.

Generation and detection of spin-orbit coupled neutron beams

Structured waves and spin-orbit coupled beams have become an indispensable probe in both light and matter-wave optics [1-2], for neutron specifically, showing distinct scattering dynamics for some samples [3-4]. We present a method of generating neutron orbital angular momentum (OAM) states utilizing 3He neutron spin filters along with four specifically oriented triangular coils and magnetic field shielding. These states are verified via their spin-dependent intensity profiles [5]. The period and OAM number of these spin-orbit states can be altered dynamically via the magnetic field strength within the coils and the total number of coils to tailor the neutron beam towards a particular application or specific material [6].

Developments in device-independent cryptography

Device-independent cryptography connects the foundational topic of Bell inequalities to the operational task of achieving secure cryptography. With significant progress being made in Bell test experiments, various avenues for further developing device-independent cryptography have been opened. I will give an overview of some background and recent developments in the field, as well as some research questions that should be of interest going forward.

EvolutionQ, founded by Norbert Lütkenhaus, Executive Director of the Institute for Quantum Computing, and IQC faculty member Michele Mosca, has secured $7 million in funding for quantum-safe cybersecurity. EvolutionQ is looking to help organizations prepare themselves for quantum computers. Their Series A financing is led by Quantonation, a Paris-based, quantum technology-focused VC fund, with support from Toronto’s The Group Ventures, to “scale up” its quantum-safe cybersecurity tech.

Detector Imperfections in QKD

Very often, in theory, device and implementation imperfections are assumed to be ideal to make the theory simpler. However, before we can practically use these devices, these assumptions must either be removed or justified. I will talk about some techniques to rigorously deal with imperfect detectors within the context of QKD.

RAC Journal Club Series featuring Bhaskaran Muralidharan, Indian Institute of Technology, Bombay

The tunneling time problem – the question on how long a particle spends inside a forbidden region, has puzzled physicists since the inception of quantum mechanics.