Cooling a Qubit using n Others

Please join us for the QSE Center Quantum Seminar with Jake Xuereb from TU Wien's Atominstitut who will give the talk "Cooling a Qubit using n Others" on Thursday January 15 from 12pm to 1:30pm.
Location: CE 1 105

Pizzas will be available at 12:00. All PhDs, postdocs, students, group leaders, and PIs are welcome to join us.

TITLE: "Cooling a Qubit using n Others" 

ABSTRACT:
When running a quantum computer, it is often necessary to reset part of the register to the all-zero state. Ideally, this should be done efficiently, without relying on highly contrived multipartite operations and without dissipating excessive heat into a classical refrigerator.

In this talk, we will explore the problem of unitarily cooling a single qubit using access to n auxiliary reservoir qubits with a given energy distribution. I will show that the achievable cooling is governed by a family of simple inequalities determined by macroscopic quantities such as the qubits’ temperatures and the total energy of the reservoir.

Remarkably, these inequalities allow the cooling problem to be mapped onto a minimum-weight perfect matching problem on Boolean hypercube graphs, translating a thermodynamic task into a problem of combinatorics. This perspective enables us to predict when cooling is efficient or inefficient depending on the reservoir’s energy structure, and to develop systematic methods for optimising cooling interactions.

Reference : arXiv:2506.10059

BIO: 

Jake Xuereb is a final-year PhD student in the group of Prof. Marcus Huber at the TU Wien's Atominstitut in Vienna. Originally from Malta, he found his way into quantum thermodynamics by way of Dublin as a visiting graduate student at Trinity College (Goold Group) and UCD (Campbell Group). His research focusses on studying how thermodynamic constraints limit an agent’s ability to process information and the development of quantum thermodynamics from an operational perspective. This avenue of research asks how the insights of quantum thermodynamics— from thermodynamic detection of entanglement to computational models based on heat exchange between quantum systems. In the community, he is known for founding the Qalypso Summer Schools which take place every other summer in Malta.