Cambridge-Warwick Quantum Computing Colloquium: Bill Fefferman (University of Chicago)

[Tom Gur]

Hi everyone,
 
The next colloquium in this series will be given by Bill Fefferman (University of Chicago), who will talk about Quantum Pseudoentanglement. See details and calendar entry below. 

The talk will take place on 25 October 2022, 2pm London time.

Zoom link: https://us02web.zoom.us/j/84881191988?pwd=dEttejBJSmR2VTFBSmtodUhxUDZIQT09
 
Best,

Tom and Sergii

 
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Bill Fefferman (University of Chicago) 

Title: Quantum pseudoentanglement 

Abstract: Quantum pseudorandom states are efficiently preparable states that are indistinguishable from truly Haar random states to an efficient observer. First defined by Ji, Liu and Song, such states have found a wide variety of applications in areas such as cryptography and quantum gravity. A fundamental question is exactly how much entanglement is required to create such states. Haar-random states, as well as t-designs, exhibit near-maximal entanglement. Here we provide the first construction of pseudorandom states with only polylogarithmic entanglement entropy across an equipartition of the qubits, which is the minimum possible. Our construction can be based on any one-way function secure against quantum attack. We additionally show that the entanglement in our construction is fully "tunable". More fundamentally, our work calls into question to what extent entanglement is a "feelable" quantity of quantum systems. Inspired by recent work of Gheorghiu and Hoban, we define a new notion which we call "pseudoentanglement", which are ensembles of efficiently constructable quantum states which hide their entanglement entropy. We show such states exist in the strongest form possible while simultaneously being pseudorandom states. 

Based on joint work with Adam Bouland, Soumik Ghosh, Umesh Vazirani and Zixin Zhou.