Seminar

In this talk, I will introduce a new security property of a cryptographic hash function that is useful for quantum cryptography. This property (1) suffices to construct pseudorandom quantum states, (2) holds for a random oracle, and thus plausibly holds for existing hash functions like SHA3, and (3) is independent of the P vs. NP question in the black box setting. This offers further evidence that one-way functions are not necessary for computationally-secure quantum cryptography. Our proof builds on recent work of Aaronson, Ingram, and Kretschmer (2022).

It is an exciting time for quantum computing where prototypes of early-stage quantum computers are becoming available at your fingertips through clouds.  Conventional computer science study of quantum computing has been focusing on its algorithm and complexity perspective.

Physics is a human activity. Doing hard science involves not only having ideas and taking data, but also convincing your peers by communicating your results in a clear fashion. In this talk, I will offer a bit of the editorial perspective from PRL on how scientific knowledge is established in papers. Our main topic will be the way papers are conceived, treated by editors, assessed by peers, and finally published.

Publicly verifiable quantum money is a protocol for the preparation of quantum states that can be efficiently verified by any party for authenticity but is computationally infeasible to counterfeit. We develop a cryptographic scheme for publicly verifiable quantum money based on Gaussian superpositions over random lattices.

We study the stellar representation of quantum computations, based on holomorphic functions, which delineates the boundary between discrete- and continuous-variable quantum information theory.

Quantum measurements are inherently probabilistic. Further defying our classical intuition, quantum theory often forbids us to precisely determine the outcomes of simultaneous measurements. This phenomenon is captured and quantified through uncertainty relations. Although studied since the inception of quantum theory, this problem of determining the possible expectation values of a collection of quantum measurements remains, in general, unsolved.

The optimal rates for compression of mixed states was found by Koashi and Imoto in 2001 for the blind case and by Horodecki and independently by Hayashi for the visible case respectively in 2000 and 2006. However, it was not known so far whether the strong converse property holds for these compression problems. In this work, we show that the strong converse holds for the blind compression scheme. For the visible scheme, the strong converse holds up to the continuity of the regularized Renyi entanglement of purification.

Randomized benchmarking protocols have become the prominent tool for assessing the quality of gates on digital quantum computing platforms.  In `classical' variants of randomized benchmarking multi-qubit gates are drawn uniformly from a finite group.  The functioning of such schemes be rigorous guaranteed under realistic assumptions.  In contrast, experimentally attractive and practically more scalable randomized benchmarking schemes often directly perform random circuits or use other non-uniform probability measures.

Lecture 3:  Bosonic Fock-state codes

I overview six use cases of bosonic encodings, three of which circumvent no-go theorems due to the infinite-dimensionality of bosonic Hilbert space.

ATL 3100A and Virtual Via Zoom

Lecture 2:  Bosonic stabilizer codes

I go over bosonic quantum memories, organizing them into bosonic stabilizer codes and bosonic Fock-state codes. 

ATL 3100A and Virtual Via Zoom