Скачать или смотреть Decoupling theorem in quantum information theory: Application and Derandomization

Title: Decoupling theorem in quantum information theory: Application and Derandomization

Speaker: Aditya Nema, Assistant Professor, IIT Gandhinagar, Gujarat.

Time: 5:30 PM - 6:30 PM (IST)

Date: 22 September 2025

Venue: MP-20 and Online on Zoom

Zoom link: https://us06web.zoom.us/j/83388976389...

Zoom Meeting ID: 833 8897 6389, Pass Code: NSSIISc

YouTube Livestream:    • Видео  

Webpage Link: https://cni.iisc.ac.in/seminars/2025-...

Abstract: In this talk, we will go through a widely applicable tool in quantum information theory called the "decoupling theorem". Decoupling is a standard technique to prove achievability results in quantum information theoretic tasks and has deep insights in several areas of quantum information including information locking, thermodynamics and even quantum gravity. A standard statement of the decoupling theorem states that if certain entropic constraints are met, then a given bipartite state can be transformed into a product state in expectation over random unitary operators, by applying a unitary operator chosen uniformly at random on one-half of the bipartite state followed by a quantum channel. This result was first proven for Haar random unitaries. We will see a quick proof sketch followed by an application for achievability of point to point quantum channel capacity.
We then take a step further to prove a novel high probability decoupling theorem with pseudo-random unitaries coming from an ensemble called approximate unitary t-designs. This is essentially a derandomization method in quantum information processing, which is analogous to the classical $t$-wise independence to reduce randomness. It is proven that the sampling and implementation of Haar random unitaries is exponentially hard and this pseudorandom ensemble of
unitaries (approximate unitary $t$-design) and can be constructed efficiently for $t=O(poly(\log n))$ (Brandao et al. (2012) and Sen (2019)).


Bio: Aditya Nema, Assistant Professor, Dept. of Electrical Engineering, IIT Gandhinagar, Gujarat. I did my Master’s and Ph.D. from STCS, TIFR, Mumbai in Quantum Information Theory. After PhD, I was a Research Assistant Prof. in Nagoya University, Japan continuing research in quantum information (Shannon) theory with applications in quantum resource theory. Then I became a postdoc researcher in the Institute of Quantum Information, Department of Physics at RWTH Aachen University. Very recently I have joined the Electrical Engineering department at IIT Gandhinagar, where I am currently an Assistant Professor. My research interests are in classical and quantum information theory, quantum computation and applied probability.
For details, see https://iitgn.ac.in/faculty/ee/fac-ad...

ALL ARE WELCOME.

Thank you,