Current graduate students

Graphical CSS Code Transformation Using ZX Calculus

Abstract: In this work, we present a generic approach to transform CSS codes by building upon their equivalence to phase-free ZX diagrams. Using the ZX calculus, we demonstrate diagrammatic transformations between encoding maps associated with different codes. As a motivating example, we give explicit transformations between the Steane code and the quantum Reed-Muller code, since by switching between these two codes, one can obtain a fault-tolerant universal gate set. To this end, we propose a bidirectional rewrite rule to find a (not necessarily transversal) physical implementation for any logical ZX diagram in any CSS code.

Then we focus on two code transformation techniques: code morphing, a procedure that transforms a code while retaining its fault-tolerant gates, and gauge fixing, where complimentary codes (such as the Steane and quantum Reed-Muller codes) can be obtained from a common subsystem code. We provide explicit graphical derivations for these techniques and show how ZX and graphical encoder maps relate several equivalent perspectives on these code transforming operations.

CS/Math seminar - Igor Klep, University of Ljubljana

The talk will discuss state polynomials, i.e., polynomials in noncommuting variables and formal states of their products. The motivation behind this theory arises from the study of correlations in quantum networks. We will give a state analog of Artin's solution to Hilbert's 17th problem showing that state polynomials, positive over all matrices and matricial states, are sums of squares with denominators.

En français

Today, on May 12th, the Institute for Quantum Computing (IQC) is joining the world-wide mathematical community in celebrating women in mathematics. On this day of recognition, IQC is featuring some of the highly accomplished women in our community to share their experience, achievements, and advice for the next generation of women in math.

13-level Qudit Measurement Demonstrated in Trapped Ions

Abstract: Qudits are an interesting alternative to qubits for a number of algorithmic reasons, but for trapped ions they could be a path for scaling. Ion traps are running into limitations on the number of qubits they can confine in a single trap, and using more of the computational space available in the ions to make qudits is an attractive solution. We have proposed using trapped ion qudits in a previous paper, developing all of the necessary quantum information protocols for their implementation. Here, we present an experimental result of a 13-level qudit measurement with a fidelity of 91.3%. The protocol can be used to measure up to a 25-level qudit in barium. The error scaling is not inherent to the dimension of the qudit, so we can envision going to higher dimensions without a significant increase in error.

En français

This winter term, the Institute for Quantum Computing (IQC) welcomed seventeen elementary school classes to our Institute to learn about quantum information science and technology, as well as ion trapping.

IQC CS/Math seminar - Marc-Olivier Renou (INRIA, Paris-Saclay)

Quantum correlations are obtained when multiple parties perform independent measurements on a shared quantum state. Bell’s seminal theorem proves that certain correlations predicted by quantum theory resist explanations in terms of any Local Hidden Variable theory based on shared randomness. But what about alternative explanations for quantum correlations, in terms of a hypothetical causal theory involving exotic bipartite resources generalising quantum bipartite entanglement in addition to shared randomness?

En français

The David Johnston Award for Scientific Outreach recognizes students who have shown an outstanding commitment to promoting public awareness of quantum research through scientific outreach and community engagement. The Institute for Quantum Computing (IQC) is proud to announce this year's award recipients: Stephen Harrigan, Sarah (Meng) Li, and Alev Orfi.

Development of InSb Surface Quantum Wells for hybrid superconducting device applications.

Abstract: Surface quantum well (QW) heterostructures in III-V semiconductors are compatible with proximitized superconductivity and offer a scalable planar platform for superconductor-semiconductor systems, such as those suggested for topological quantum computation and those suitable for topological phase transitions involving Majorana zero modes. Amongst III-V binary semiconductors, Indium Antimonide (InSb) has the smallest electron effective mass, highest spin orbit coupling and largest Land´e g-factor. Such material properties makes the pursuit of InSb QWs desirable for a number of quantum device applications, including quantum sensing, quantum metrology, and quantum computing.

Unfortunately, high quality two-dimensional electron gases (2DEGs) in InSb QWs have so far been difficult to realize. InSb QWs have generally relied on the use of modulation doping for 2DEG formation, but these structures have frequently reported issues with parasitic parallel conduction and unstable carrier densities. We report on the transport characteristics of field effect 2DEGs in surface InSb quantum wells which overcome these challenges and are suitable for future hybrid superconducting device applications.

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En français

In the first allocation of NSERC Alliance Quantum Grant funding, announced today by NSERC, many faculty members, affiliates, and alumni of the Institute for Quantum Computing (IQC) are leading or collaborating on projects receiving support.

En français

At the Institute for Quantum Computing (IQC), every day is a quantum day. But today, on April 14th, we are especially excited to join a community of scientists around the world in the celebration and promotion of the public understanding of quantum science and technology.

Current graduate students

IQC Student Seminar featuring Sarah Meng Li

Graphical CSS Code Transformation Using ZX Calculus

Positive state polynomials

CS/Math seminar - Igor Klep, University of Ljubljana

IQC celebrates women in mathematics

IQC Student Seminar featuring Brendan Bramman

13-level Qudit Measurement Demonstrated in Trapped Ions

IQC outreach welcomes elementary school students

Any Physical Theory of Nature Must Be Boundlessly Multipartite Nonlocal

IQC CS/Math seminar - Marc-Olivier Renou (INRIA, Paris-Saclay)

IQC researchers honoured for excellence in scientific outreach

IQC Student Seminar featuring Emma Bergeron

IQC members awarded millions in NSERC Quantum Alliance funding

IQC celebrates world quantum day

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