October 2022 - Quantum-info-group

[Harvard-quantum-initiative] Harvard Quantum Information Meeting

by Xun Gao

Dear all, This week will be the fifth "Harvard Quantum Information Group Meeting", which will be held on Thursday, October 27th at 4:30 pm in Jefferson 250. This week, Chinmay Nirke from IBM will talk about the complexity of quantum proofs. Title: Classical oracle separations between QMA and QCMA (joint work with Anand Natarajan, MIT) Abstract: It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (QMA) or if classical witnesses suffice (QCMA). We make progress on this question by constructing a randomized classical oracle separating the respective computational complexity classes. Previous separations [Aaronson-Kuperberg, Fefferman-Kimmel] required a quantum unitary oracle. The separating problem is deciding whether a distribution supported on regular un-directed graphs either consists of multiple connected components (yes instances) or consists of one expanding connected component (no instances) where the graph is given in an adjacency-list format by the oracle. Therefore, the oracle is a distribution over n-bit boolean functions. In this talk, I will give a more pedagogical introduction to the subject – including how to think about the complexity of quantum proofs. Questions are welcome, especially from audience members unfamiliar with the area! Here is the link of <https://calendar.google.com/calendar/u/0?cid=Y185MWI0YjdkMWE3YmJjYzkwODNlNT…>google calenda <https://calendar.google.com/calendar/u/0?cid=Y185MWI0YjdkMWE3YmJjYzkwODNlNT…>r for the next few meetings. The meeting is open to everyone at Harvard interested in quantum information, including those in condensed matter physics, AMO physics, high energy physics, computer science, chemistry, etc. The format includes weekly tutorials (by both external and internal speakers) of contemporary topics in quantum information and quantum computing, aimed for a broad scientific audience. We will also try to foster connections between different groups at Harvard which are interested in or involved with quantum information, and build a broader community. Hope to see you all there. If you would like to join the mailing list for this meeting, please e-mail harvardqimeeting(a)gmail.com <mailto:harvardqimeeting@gmail.com> which will add you.

1 year, 7 months

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[Harvard-quantum-initiative] Harvard Quantum Information Meeting

by Xun Gao

Dear all, This week will be the fourth "Harvard Quantum Information Group Meeting", which will be held on Thursday, October 20th at 4:30 pm in Jefferson 250. This week, Roy Garcia from Prof. Arthur Jaffe’s group will talk. Title: Resource theory of quantum scrambling Abstract: Quantum scrambling refers to the spread of local quantum information into the many degrees of freedom of a quantum system. In this work, we introduce a resource theory of scrambling which incorporates two mechanisms, "entanglement scrambling" and "magic scrambling". We introduce two resource monotones called the Pauli growth and the OTOC (out-of-time-ordered correlator) magic for these two mechanisms, respectively. We use our resource theory to explain recent experimental observations of magic. We also show that both resource monotones can be used to bound the decoding fidelity in Yoshida's black hole decoding protocol. These applications provide an operational interpretation of the resource monotones defined in this work. Here is the link of <https://calendar.google.com/calendar/u/0?cid=Y185MWI0YjdkMWE3YmJjYzkwODNlNT…>google calenda <https://calendar.google.com/calendar/u/0?cid=Y185MWI0YjdkMWE3YmJjYzkwODNlNT…>r for the next few meetings. The meeting is open to everyone at Harvard interested in quantum information, including those in condensed matter physics, AMO physics, high energy physics, computer science, chemistry, etc. The format includes weekly tutorials (by both external and internal speakers) of contemporary topics in quantum information and quantum computing, aimed for a broad scientific audience. We will also try to foster connections between different groups at Harvard which are interested in or involved with quantum information, and build a broader community. Hope to see you all there. If you would like to join the mailing list for this meeting, please e-mail harvardqimeeting(a)gmail.com <mailto:harvardqimeeting@gmail.com> which will add you.

1 year, 7 months

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[Harvard-quantum-initiative] Harvard Quantum Information Meeting

by Xun Gao

Dear all, This week will be the third "Harvard Quantum Information Group Meeting", which will be held on Thursday, October 13th at 4:30 pm in Jefferson 250. This week, Eddie Farhi will talk about QAOA. Title: Virtues of the Quantum Approximate Optimization Algorithm Abstract: I will review how the QAOA works, and show how to obtain worst case performance guarantees, and discuss how it has quantum supremacy at the shallowest depth. I will also describe its performance on an all-to-all connected spin glass model in the infinite size limit. Other stuff as time permits. The meeting is open to everyone at Harvard interested in quantum information, including those in condensed matter physics, AMO physics, high energy physics, computer science, chemistry, etc. The format includes weekly tutorials (by both external and internal speakers) of contemporary topics in quantum information and quantum computing, aimed for a broad scientific audience. We will also try to foster connections between different groups at Harvard which are interested in or involved with quantum information, and build a broader community. Hope to see you all there. If you would like to join the mailing list for this meeting, please e-mail harvardqimeeting(a)gmail.com <mailto:harvardqimeeting@gmail.com> which will add you.

1 year, 7 months

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[Thusem] [Harvard-quantum-initiative] Harvard Quantum Information Meeting

by Xun Gao

Dear all, This week will be the second "Harvard Quantum Information Group Meeting", which will be held on Thursday, October 6th at 4:30 pm in Jefferson 250. This week, Daniel Ranard from MIT will talk about entanglement bootstrap. Title: From Markov states to anyons Abstract: In this pedagogical talk, I will introduce quantum Markov states and their application in many-body physics. The basic concepts include Markov chains, conditional mutual information, and recovery maps [1]. As one application, I discuss how these tools can be used to understand thermal states and prepare them on a quantum computer [2]. I will focus on how these tools can be used to analyze 2D topological phases [3]. Related references: [1] Sutter, arXiv:1802.05477 [2] Brandao and Kastoryano, arXiv:1609.07877 [3] Shi, Kato, Kim, arXiv:1906.09376 The meeting is open to everyone at Harvard interested in quantum information, including those in condensed matter physics, AMO physics, high energy physics, computer science, chemistry, etc. The format includes weekly tutorials (by both external and internal speakers) of contemporary topics in quantum information and quantum computing, aimed for a broad scientific audience. We will also try to foster connections between different groups at Harvard which are interested in or involved with quantum information, and build a broader community. Hope to see you all there. If you would like to join the mailing list for this meeting, please e-mail harvardqimeeting(a)gmail.com <mailto:harvardqimeeting@gmail.com> which will add you.

1 year, 7 months

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Quantum-info-group October 2022