Events

Stable and Localized Emission from Ambipolar Dopant-Free Lateral p-n Junctions

Quantum-Nano Centre, 200 University Ave West, Room QNC 1201 Waterloo, ON CA N2L 3G1

Combining the architectures of a dopant-free lateral p-n junction and a single-electron pump in a GaAs/AlGaAs heterostructure material system could yield high-rate, electrically-driven quantum emitters with performances surpassing the competition in quantum sensing, communication and cryptography. Observed drawbacks of the dopant-free p-n junctions are a rapid decay in electroluminescence during operation, as well as delocalized emission that lowers the measured quantum efficiency. This talk details novel measurement protocols and gate architectures implemented by us to overcome these challenges.

Blackbox Optimization for Free-space Quantum Key Distribution

MC, 200 University Ave West, Room MC 5417
Waterloo, ON CA N2L 3G1

Supervisors: Thomas Jennewein and Norbert Lütkenhaus

Weight estimation for optical detection setups

QNC building, 200 University Ave. Room 1201, Waterloo 

Realistic models of optical detection setups are crucial for numerous quantum information tasks. For instance, squashing maps allow for more realistic descriptions of the detection setups by accounting for multiphoton detections. To apply squashing maps, one requires a population estimation of multiphoton subspaces of the input to the detection setup. So far, there has been no universal method for those subspace estimations for arbitrary detection setups.

We introduce a generic subspace estimation technique applicable to any passive linear optical setup, accounting for losses and dark counts. The resulting bounds are relevant for adversarial tasks such as QKD or entanglement verification. Additionally, this method enables a generic passive detection setup characterization, providing the necessary measurement POVM for e.g. QKD security proofs.

IQC Colloquium - Dr. Chae-Yeun Park, Xanadu

QNC building, 200 University Ave. Room QNC 1201 Waterloo 

Understanding the dynamics of quantum many-body systems is one of the fundamental objectives of physics. The existence of an efficient quantum algorithm for simulating these dynamics with reasonable resource requirements suggests that this problem might be among the first practically relevant tasks quantum computers can tackle. Although an efficient classical algorithm for simulating such dynamics is not generally expected, the classical hardness of many-body dynamics has been rigorously proven only for certain commuting Hamiltonians. In this talk, I will show that computing the output distribution of quantum many-body dynamics is classically difficult, classified as #P-hard, also for a large class of non-commuting many-body spin Hamiltonians. Our proof leverages the robust polynomial estimation technique and the #P-hardness of computing the permanent of a matrix. By combining this with the anticoncentration conjecture of the output distribution, I will argue that sampling from the output distribution generated by the dynamics of a large class of spin Hamiltonians is classically infeasible. Our findings can significantly reduce the number of qubits required to demonstrate quantum advantage using analog quantum simulators.

Douglas Stebila, University of Waterloo

QNC building, 200 University Ave. Room 1201, Waterloo 

This workshop will provide an introduction to the Tamarin prover, which is a security protocol verification tool that analyzes cryptographic protocols in a symbolic model and can automatically identify attacks or conclude that certain classes of attacks do not exist. The workshop will include a hands-on exercise using the Tamarin prover.

To attend this program please email us at cryptoworks21@uwaterloo.ca by July 16, 2024.

Elena Bakos Lang and Kevin Henry, NCC Group

QNC building, 200 University Ave. Room 1201, Waterloo 

The security of cryptographic primitives and protocols is inextricably tied to that of the implementations deployed in the real world. Ensuring that these implementations are as secure as possible is thus a problem at the heart of cryptographic security.

This workshop will introduce common classes of cryptographic vulnerabilities, including improper randomness generation, side-channel attacks, flaws in primitives or protocols, and others, and discuss secure coding practices that can help mitigate them, based on our experiences auditing cryptographic code. This discussion will be complemented by a set of practical exercises to provide experience in spotting insecure constructions. Additionally, as implementation quality is often tied to the quality of the source material, we will present a case study on a recent widely implemented threshold signing protocol where ambiguous or unclear presentation in the academic source material has led to multiple critical implementation vulnerabilities.

This workshop is presented by NCC Group Cryptography Services practice in Waterloo, Ontario.

To attend this program please email us at cryptoworks21@uwaterloo.ca by July 17, 2024.

The QKD security proof workshop is an annual workshop series focused on technical security proofs. Our focus in the workshop is to facilitate interactions and discussions between participants.