Our Focus

The Center for Quantum Science and Engineering (CQSE) was recently established by the
School of Engineering and Applied Science and the Division of Physical Sciences at UCLA to coordinate
research and teaching activities in the emerging field of quantum information science and technology.
CQSE is also developing new approaches to education in this emerging discipline.

What is CQSE?

The UCLA CQSE was recently featured by the Amercan Physical Society in their APS TV series on academic institues and centers. The video gives an overview of CQSE activites through short interviews with Center faculty, students and industry collaborators.


Ansatz-Independent Variational Quantum Classifier

Recently, variational quantum algorithms (VQAs) have attracted much attention and are possible candidates for utilizing near-term quantum devices. However, VQAs require an ansatz on a quantum circuit. In other words, to simulate VQAs, a circuit geometry must be fixed a priori and then optimized for the parameters of the gates in the circuit. But the performance of VQAs heavily depends on the ansatz, and a search over all possible ansatz is computationally infeasible. This makes an assessment of the full power of VQAs infeasible, and an alternate solution is needed.

In a recent paper, Hideyuki Miyahara and Vwani Roychowdhury have proposed a method that can indeed create such an ansatz-independent variational quantum classifier, which they call the unitary kernel method (UKM). The UKM gives an upper bound on the performance of variational quantum classifiers (VQC), which are a subset of VQAs, and thus addresses an important open problem. Extensive numerical results provide strong supporting evidence how the UKM consistently performs better than the ansatz-dependent methods, such as quantum circuit learning (QCL). Another main contribution of their paper is to propose a method to construct a circuit geometry from a given unitary operator, which they call the variational circuit realization (VCR). By combining the UKM and the VCR, a circuit geometry can be constructed efficiently thus not only improving the performance of VQCs, but also provide matching circuits.

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Latest News

Army Research Office Taps UCLA Engineering Team to Lead Quantum Network Research

A UCLA electrical and computer engineering team is set to lead a multi-university group of researchers that has received a three-year, $3.75 million grant from the Army Research Office (ARO) to develop secure communication networks built on quantum mechanics.

The UCLA team consists of CQSE member Professor Chee Wei Wong, who holds UCLA’s Carol and Lawrence E. Tannas, Jr. Endowed Term Chair in Engineering; Xiang Cheng; Kai-Chi Chang and Murat Sarihan of the Mesoscopic Optics and Quantum Electronics Laboratory. The researchers will use network science knowledge to create, test and explore cross-disciplinary approaches to quantum-mechanics-based networks. These foundational and applied efforts will help pave the way to the creation of interconnected quantum networks in the United States.

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UCLA Engineering Faculty Receives NSF Grant to Improve Quantum Computing Chips

Kang Wang, a UCLA electrical and computer engineering professor and his colleagues received a one-year, $920,000 grant from the National Science Foundation (NSF) to develop a new class of interconnect technology for future quantum computing.

Quantum computers offer the tantalizing promise of unprecedented computing power and speed — far exceeding even that of today’s best supercomputers. The NSF’s Convergence Accelerator program supports multidisciplinary research efforts to realize such advancements.

Led by Wang, Raytheon Professor of Electrical Engineering at the UCLA Samueli School of Engineering, and co-PI Clarice Aiello, assistant professor of electrical and computer engineering, the project will explore how to improve quantum computing chips.

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Compilation for Quantum Computing: Gap Analysis and Optimal Solution

Prof. Jason Cong recently delivered a talk at IBM Research on compilation optimization for quantum circuits. The abstract and a link to his presentation are below.

As quantum computing devices continues to scale up, it's important to access the quality of the existing quantum compilation (or design automation) tools. As the first step, we focus on the layout synthesis step. We develop a novel method to construct a family of quantum circuits with known optimal, QUEKO, which have known optimal depths and gate counts on a given quantum device coupling graph. With QUEKO, we evaluated several leading industry and academic LSQC tools, including Cirq from Google, Qiskit from IBM, and t|ket> from CQC. We found rather surprisingly large optimality gaps, up to 45x on even near-term feasible circuits. Then, we went on to develop a tool for optimal layout synthesis for quantum computing, named OLSQ, which formulates LSQC as a mathematical optimization problem. OLSQ more compactly represents the solution space than previous optimal solutions and achieved exponential reduction in computational complexity. Experimental results show that it achieves orders-of-magnitude reductions in runtime and memory usage. Compared to the leading solutions, OLSQ can reduce 70% SWAP counts on a set of arithmetic quantum circuits, and increase fidelity by 1.3x. Further improvement is achieved for QAOA (quantum approximate optimization algorithm) circuits using domain-specific knowledge.

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648 Hilbert-space dimensionality in a biphoton frequency comb: Entanglement of formation and Schmidt mode decomposition

Kai-Chi Chang, Xiang Cheng, and Chee Wei Wong, professor of electrical and computer engineering, recently published an article in npj Quantum Information on high-dimensional entanglement of photons.

High-dimensional entanglement with larger Hilbert spaces enable an encoding of more bits per photon and thus promise increased communication capacities over quantum channels. Quantum frequency combs, which are intrinsically multimode in the temporal and frequency degrees of freedom within a single spatial mode, naturally facilitating the generation and measurement of high-dimensional entanglement. Current challenges include the extension of well-known methods for two qubits to high-dimensional quantum systems and their application in entanglement experiments with photons. More specifically, the major challenge is the certification of high-dimensional entanglement by a number of accessible experimental measurements. In this paper, we increase the Hilbert space dimensionality and provide versatile tools for quantifying and certifying high-dimensional entanglement in a biphoton frequency comb. We quantify the time-binned Schmidt number up to 18 and certify entanglement of formation with 1.89 ebits. We have demonstrated a 648-dimensional Hilbert spaces with time-frequency entanglement in a biphoton frequency comb, enabling a computational space up to 13 photonic qubits, and 6.28 bits/photon classical information capacity. This high-dimensional time-frequency multimode quantum states of biphoton frequency comb significantly boosting the photon information capacity that is critical for large-scale quantum information processing. Biphoton frequency comb has indeed demonstrated an attractive and powerful approach towards achieving this fundamental goal with applications in high-dimensional quantum information processing, time-frequency cluster-state quantum computation, high-dimensional encoding in quantum networks, and high-dimensional quantum simulations.

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Prof. Jens Palsberg presents "Quantum education at scale" at the Google Quantum Summer Symposium

Prof. Jens Palsberg, one of our CQSE faculty members, recently delivered a lecture at the Google Quantum Summer Symposium 2021 on his experience with teaching quantum courses in the Computer Science department at UCLA. Over the last three years, 200 students have taken his UCLA quantum course, run programs on quantum computers, and given him great teaching evaluations. He explains in the lecture how he gives students quantum knowledge, skills, and agency and how it can be done at scale. He explains how he set up his course as a learning lab that values learning from each other, how he went for breadth such that every student can find something of interest, and how he let the students loose on two quantum computers. He also discusses the new Quantum Science and Technology Master's program starting at UCLA in Fall 2022.

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Quantum Computing Student Association

We are excited to announce the formation of a new UCLA club, the Quantum Computing Student Association. We are a community of undergraduate and graduate students who share an interest in quantum computing and quantum information science. QCSA is part of the Center for Quantum Science and Engineering (CQSE) at UCLA. QCSA members work with CQSE faculty in both experimental and theoretical quantum computing research projects. We are an interdisciplinary group: together, our research projects and fields of study span many departments, including physics, computer science, electrical engineering, bioengineering, math, and chemistry/materials science.

We have a Slack channel for announcements and discussions outside of meetings. We are currently setting up a calendar of events for the Fall 2021 quarter. To learn more and to join, visit our website today!



CQSE Seminar Series

The CQSE Seminar series will resume in virtual format in the fall. The schedule is being organized now. Below are the past talks from Winter and Spring quarters. If you are interested in attending future seminars, please contact us to get the link.

January 28, 10 am: Peter Zoller, University of Innsbruck

March 25, 10 am: Alan Aspuru-Guzik, University of Toronto

Apr 29, 10 am: Misha Lukin, Harvard University

May 27, 10 am: Emina Soljanin, Rutgers University 

June 24, 4 pm: Andrew Dzurak, University of New South Wales

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