Universal protocols for transforming unitary quantum operations: Exponential advantage with adaptive protocols and the power of indefinite causality

Marco Túlio


University of Vienna

March 18, 2021 3:15 AM


Given a general d-dimensional unitary operation U for which, apart from the dimension, its description is unknown, is it possible to implement f(U)? How does the situation change when k uses of unitary operation U are allowed? In this talk we address how to obtain such transformations via quantum circuits and general superchannel, considering probabilistic exact and deterministic non-exact transformations.
For unitary inversion and unitary transposition we present an explicit sequential circuit which attain an exact transformation with a failure probability that decays exponentially in the number of uses k. We discuss arbitrary transformations on quantum unitary operations, deterministic non-exact protocols are considered and the power of indefinite causality for transforming unitary operations.

The main content of this talk will be based on two published and on another work in collaboration with Daniel Ebler which we're now finishing writing. The published ones are:

[1] Marco Túlio Quintino, Qingxiuxiong Dong, Atsushi Shimbo, Akihito Soeda, Mio Murao, Reversing Unknown Quantum Transformations: Universal Quantum Circuit for Inverting General Unitary Operations, Phys. Rev. Lett. 123, 210502 (2019).

[2] Marco Túlio Quintino, Qingxiuxiong Dong, Atsushi Shimbo, Akihito Soeda, Mio Murao, Probabilistic exact universal quantum circuits for transforming unitary operations, Phys. Rev. A 100, 062339 (2019). 


Zoom meeting details 

Topic: Quantum Information and Quantum Computing Working Group
Time: March 18, 2021, 3:15 PM Warsaw
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Meeting ID: 96294497969
Passcode: 729533

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