Southwest Quantum Information and Technology

Efficiency-Fidelity Trade-off in a Quantum Error Correcting Engine

Presenting Author: Arshag Danageozian, Louisiana State University
Contributing Author(s): Francesco Buscemi, Mark M. Wilde

Quantum error correction (QEC) is a procedure by which the quantum state of a system is protected against a known type of noise by preemptively adding redundancy to it using an ancillary system. A major type of noise that regularly appears in almost every implementation of quantum computing and QEC is thermal noise, which is also known to play a central role in quantum thermodynamics (QTD). This fact hints at the applicability of certain QTD statements in the QEC of thermal noise. Such statements have been discussed previously in the context of Maxwell's demon. In this article, we view QEC as a quantum heat engine with a feedback controller (demon). The main task of this engine is to correct the effects of the hot bath (thermal noise) by attempting to close its own cycle with respect to the system state, corresponding to a perfect QEC. We derive Clausius' formulation of the second law in the context of this QEC engine operating with general quantum measurements. For efficient measurements and sufficiently low temperatures of the cold bath, we show that this leads to a fundamental trade-off between the fidelity of the error-corrected system state and the super-Carnot efficiencies that heat engines with feedback controllers have been known to possess.

(Session 6 : Friday from 3:10pm-3:30pm)