The Institute for Quantum Computing (IQC) congratulates Alain Aspect, John F Clauser and Anton Zeilinger who have been awarded the 2022 Nobel Prize in physics.
Quantum-classical correspondence is of fundamental interest as it allows for computing and analysing the quantum properties with respect to their classical counterparts. This helps us study the transition from the quantum to the classical. According to the correspondence principle, quantum mechanics should agree with classical mechanics in appropriate limits. In our first project, we show that currently available NISQ computers can be used for versatile quantum simulations of chaotic systems. We introduce a classical-quantum hybrid approach for exploring the dynamics of the chaotic quantum kicked top (QKT) on a universal quantum computer. The programmability of this approach allows us to experimentally explore the complete range of QKT chaoticity parameter regimes inaccessible to previous studies. Furthermore, the number of gates in our simulation does not increase with the number of kicks, thus making it possible to study the QKT evolution for arbitrary number of kicks without fidelity loss. Using a publicly accessible NISQ computer (IBMQ), we observe periodicities in the evolution of the 2-qubit QKT, as well as signatures of chaos in the time-averaged 2-qubit entanglement. We also demonstrate a connection between entanglement and delocalization in the 2-qubit QKT, confirming theoretical predictions. However, the connection between classical and quantum mechanics is not straightforward, especially in chaotic systems. The question of why a chaotic system, in certain situations, breaks the correspondence principle remains one of the open questions. Nevertheless, the breaking of Quantum classical correspondence for a large system i.e., the large value of j (but finite), is surprising. It suggests that the system never behaves classically in certain situations, irrespective of the system size. It is also worth exploring this strange behavior from an experimental point of view, as it will decide the parameters of the experimental setup designed for studying Quantum Chaos.
Meet graduate student researchers from science, engineering, and mathematics and hear how they discovered quantum information science, found their way into research, and how the skills they gained in their undergraduate studies are helping them develop the next generation of quantum technology.
There's growing awareness of the lack of diversity in science and the presence of barriers to inclusion. What factors lead to disparities in representation? Why should we be motivated to effect change? What can we do to change things? Will our actions really make a difference?
This presentation will focus on ideas to challenge the status quo – actions to advance equity, diversity, and inclusion (EDI). We will discuss recent research to illustrate and raise awareness of the many EDI challenges in science, then explore various practical ways to take action to advance EDI. These practical actions stem from our recently released "Science is For Everyone" Teaching toolkit, which provides an abundance of ideas to diversify science education and further support recruitment, retention, and advancement of all students. We will touch on the importance of diversifying content and talk about how Indigenous content is being brought into post-secondary science courses. Finally, we will give an overview of other exciting science EDI initiatives across research and academic life.
Join us for Quantum Today, where we sit down with researchers from the University of Waterloo’s Institute for Quantum Computing (IQC) to talk about their work, its impact and where their research may lead.
TQT’s Quantum For Health (Q4Health), is open to all at the University of Waterloo, seeking opportunities where quantum can advance health.
On September 19, TQT will host a Q4Health Launch Event in the Mike and Ophelia Lazaridis Quantum-Nano Centre Rm 0101. This event will include descriptions of quantum for health case studies. Following the talks, there will be a meet and greet to assist in team building. Attendees will receive information updates and an opportunity to register and learn more about upcoming Lunch and Learn sessions.
Register by September 16 (for refreshment planning purposes). There will be limited onsite registration at the event.
The Jaynes-Cummings Model (JCM) approximates the Quantum Rabi Model (QRM) in some regimes and is exactly solvable by only keeping the rotating or `energy-conserving’ terms and dropping the counter-rotating or `non-energy conserving’ terms.
Since the proposal of the JCM, questions on the effect and presence of counter-rotating terms popped up.
Using strong driving, one can induce the effects of the counter-rotating terms on a comparable timescale to the rotating terms. In such a scenario, one can create a Schrödinger cat state in a resonant manner without the need for any type of Kerr nonlinearity.
In this talk, we review the QRM and its descendant, the JCM. Then, we discuss the realization of a Schrödinger cat state, its challenges in practice and how to solve them.
Developing new quantum algorithms is a famously hard problem. The lack of intuition concerning the quantum realm makes constructing quantum algorithms that solve particular problems of interest difficult. In addition, modern hardware limitations place strong restrictions on the types of algorithms which can be implemented in noisy circuits. These challenges have produced several solutions to the problem of quantum algorithm development in the modern Near-term Intermediate Scale Quantum (NISQ) Era. One of the most prominent of these is the use of classical machine learning to discover novel quantum algorithms by minimizing a cost function associated with the particular application of interest. This quantum-classical hybrid approach, also called Variational Quantum Algorithms (VQAs), has attracted major interest from both academic and industrial researchers due to its flexible framework and expanding list of applications - most notably optimization (QAOA) and chemistry (VQE). What is still unclear is whether these algorithms will deliver on their promise when implemented at a useful scale, in fact there is strong reason to worry whether the classical machine learning model will be able to train in the larger parameter space. This phenomenon is commonly referred to as the Barren Plateaus problem, which occurs when the training gradient vanishes exponentially quickly as the system size increases. Recent results have shown that some cost functions used in training can be proven to result in a barren plateau, while other cost functions can be proven to avoid them. In this presentation, I apply these results to my 2018 paper where my group developed a new Variational Quantum State Diagonalization (VQSD) algorithm and so demonstrate that this algorithm's current cost function will encounter a Barren Plateau at scale. I then introduce a simple modification to this cost function which preserves its function while ensuring trainability at scale. I also discuss the next steps for this project where I am teaching a team of 6 quantum novices across 4 continents the core calculation I use in this work to expand my analysis to the entire literature of VQAs.
A quantum computer attains computational advantage when outperforming the best classical computers running the best-known algorithms on well-defined tasks. No photonic machine offering programmability over all its quantum gates has demonstrated quantum computational advantage: previous machines were largely restricted to static gate sequences. I will discuss a quantum computational advantage using Borealis, the latest of Xanadu’s photonic processors offering dynamic programmability and available on the cloud. This work is a critical milestone on the path to a practical quantum computer, validating key technological features of photonics as a platform for this goal.
IQC Achievement Award winner Bowen Yang sat down with us to discuss his PhD research in quantum materials, the opportunities he’s received while at IQC, and his recommendations for students interested in learning and gaining more experience with quantum.