Michał Studziński | LIP6 - Équipe QI

Michał Studziński - Entanglementrecycling in quantum universal programmable processors

Mon, 26 May 2025 00:00:00 +0000

Entanglementrecycling in quantum universal programmable processors

Ce séminaire, donné par Michał Studziński, aura lieu le 26 May 2025, à 9:0. Il aura lieu en salle 24-25/405.

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Résumé

We study a model of a quantum universal programmable processor basedon variants of port-based teleportation schemes. The main goal ofthis talk is to evaluate the performance of such a processor aftermultiple rounds of execution, with the quantum program encoded withinit. We analytically characterize the degradation of the processorand, in the case where the resource state consists of N EPR pairs, wedemonstrate the possibility of reusing it for subsequent rounds ofteleportation in the limit N→∞. For an optimized processor, wecompare the performance of the protocol to that of multi-port-basedteleportation, showing that resource state reuse remains possible.Results are presented for both probabilistic and deterministicprocessors and rely on mathematical tools inspired by the mixedSchur-Weyl duality. Speaker: Michał Studziński, International Centre for Theory of QuantumTechnologies, University of Gdańsk, Poland

Multicopy quantum state teleportation with application to storage and retrieval of quantum programs

Sat, 21 Sep 2024 00:00:00 +0000

This work considers a teleportation task for Alice and Bob in a scenario where Bob cannot perform corrections. In particular, we analyse the task of \textit{multicopy state teleportation}, where Alice has $k$ identical copies of an arbitrary unknown $d$-dimensional qudit state $\vert\psi\rangle$ to teleport a single copy of $\vert\psi\rangle$ to Bob using a maximally entangled two-qudit state shared between Alice and Bob without Bob’s correction. Alice may perform a joint measurement on her half of the entangled state and the $k$ copies of $\vert\psi\rangle$. We prove that the maximal probability of success for teleporting the exact state $\vert\psi\rangle$ to Bob is $p(d,k)=\frac{k}{d(k-1+d)}$ and present an explicit protocol to attain this performance. Then, by utilising $k$ copies of an arbitrary target state $\vert\psi\rangle$, we show how the multicopy state teleportation protocol can be employed to enhance the success probability of storage and retrieval of quantum programs, which aims to universally retrieve the action of an arbitrary quantum channel that is stored in a state. Our proofs make use of group representation theory methods, which may find applications beyond the problems addressed in this work.

Optimal universal quantum circuits for unitary complex conjugation

Fri, 31 Mar 2023 00:00:00 +0000