Current graduate students

Entanglement distillation and DIQKD

QNC building, 200 University Ave. Room 1201, Waterloo 

Quantum entanglement can be quantified in many ways, some of which bear clear operational meanings. The Distillable Entanglement and DIQKD rate are two such measures, speculated to be equivalent as stated by the Revised Peres Conjecture (Friedman and Leditzky, 21). Our research lays foundations to the conjecture’s proof, most notably using the notion of ‘private states’, a family of quantum states that arise naturally in the context of QKD.  Asking questions such as “what kind of private state can be resulted from a certain DIQKD protocol?”, we were able to provide simple sufficient conditions for the Revised Peres Conjecture to hold.

Professor Christine Muschik, Institute for Quantum Computing

RAC building, 475 Wes Graham Way, Waterloo Room 3003

This week's summer tutorial session will cover quantum error correction, starting from an overview of early successes in the field before introducing stablizer codes. 

Fermion-to-qubit mappings and their error mitigating properties

QNC building, 200 University Ave. Room 1201, Waterloo 

 As we move towards the era of quantum computers with 1000+ qubits, the most promising application able to harness the potential of such devices is quantum simulation. Simulating fermionic systems is both a well-formulated problem with clear real-world applications and a computationally challenging task. In order to simulate a system of fermions on a quantum computer, one has to map the fermionic Hamiltonian to a qubit Hamiltonian. The most popular such mapping is the Jordan-Wigner encoding, which suffers from inefficiencies caused by the non-locality of the encoded operators. As a result, alternative local mappings have been proposed that solve the problem of long encoded operators at the expense of constant factor of qubits. Some of these alternative mappings end up possessing non-trivial stabilizer structure akin to popular quantum error correction (QEC) codes. 

In this talk, I will introduce the problem of mapping fermionic operators to qubit operators and how the selection of an encoding could affect resource requirements in near-term simulations. I will also talk about error mitigation approaches utilizing the stabilizer structure of certain encodings as well as using stabilizer simulation to assess the effectiveness of such approaches.

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.

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.

Daniel Nino, Xanadu

QNC building, 200 University Ave. Room 1201, Waterloo 

Xanadu is a Canadian quantum computing company with the mission to build quantum computers that are useful and available to people everywhere. Xanadu is one of the world’s leading quantum hardware and software companies and also leads the development of PennyLane, an open-source software library for quantum computing and application development.

Through this workshop, attendees will be given a broad overview of some applications of quantum computing to quantum chemistry. Through a series of hands-on exercises, attendees will learn about some PennyLane functionalities for workflows in quantum chemistry. By the end of the session, they will have hands-on experience in building quantum programs with PennyLane and how to use PennyLane datasets in applications to reduce time to research.

Please bring a laptop with you for this session. The workshop will run over Google Colab, no specific installation is required.

Improving information transmission using correlated auxiliary noise

QNC building, 200 University Ave. Room 1201, Waterloo 

Communicating information is a fundamentally important task that is often limited by noise. The physical origin of noise in a quantum channel is an interaction between the transmitted system and its surrounding environment. This interaction leads to correlations between the system and its environment that contain information about the original state, but are inaccessible to the receiver. However, a receiver may be able to recover some of this lost information if they are given access to an additional auxiliary system that interacts with the environment. In this talk, I will formalize a particular type of receiver side information and characterize the resulting improvement in classical and quantum channel capacities for an augmented bit flip channel. I will then discuss information-theoretic bounds on imperfect one-time pad cryptography schemes and passive environment-assisted quantum channel capacities.

IQC CS/Math Seminar, Xiangling Xu INRIA Saclary

QNC building, 200 University Ave. Room 1201, Waterloo 

Characterizing quantum correlations is a fundamental task in the study of quantum information theory. In the standard Bell scenario, where the correlations are established by a single source, the seminal work [Navascúes et al., 2008] presents a convergent hierarchy that provides an outer approximation, which can be formulated as a problem solvable by computers.

In the more general networks scenarios, however, the correlations are due to multiple independent quantum sources. This necessitates a generalization of the NPA hierarchy. Based on [Renou, Xu, Ligthard, 2022], this talk focuses on the simplest quantum network, the bilocal scenario, where two independent quantum sources exist: one shared between Alice and Bob, and the other between Bob and Charlie. It will discuss two convergent generalizations of the NPA hierarchy in this context, demonstrating that the bilocal scenario is completely understood from the algebraic/Heisenberg perspective.

Despite this progress, the characterization of quantum networks beyond the bilocal scenario remains an open question. This talk will introduce a possible approach, the inflation-NPA hierarchy, as a potential solution. The aim is to motivate the audience to explore this important and challenging problem further.

QNC building, 200 University Ave. Room 0101, Waterloo 

This workshop focuses on encoding quantum information in more than two states.

The main theme is to go beyond binary encodings: from quBits to quDits, where D > 2.

Now is a very interesting time, as we see a lot of experimental progress and new possibilities in this area. This workshop brings together researchers  – both experimentalists and theorists – to explore quDit-based applications in all areas of quantum technology.