The nonequilibrium cost of accurate information processing

Journal article

In order to unitarily evolve a quantum system, an agent requires knowledge of time, a parameter which no physical clock can ever perfectly characterise. In this letter, we study how limitations on acquiring knowledge of time impact controlled quantum operations in different paradigms. We show that the quality of timekeeping an agent has access to limits the gate complexity they are able to achieve within circuit-based quantum computation. It also exponentially impacts state preparation for measurement-based quantum computation. Another area where quantum control is relevant is quantum thermodynamics. In that context, we show that cooling a qubit can be achieved using a timer of arbitrary quality for control: timekeeping error only impacts the rate of cooling and not the achievable temperature. Our analysis combines techniques from the study of autonomous quantum clocks and the theory of quantum channels to understand the effect of imperfect timekeeping on controlled quantum dynamics.Comment: 5 + 7 pages, 2 figure

Authors: Chiribella, G; Meng, F; Renner, R; Yung, M-H

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature Communications
• Volume: 13
• Issue: 1
• Pages: 7155-7155
• Article number: 7155
• Publication date: 2022-11-22
• DOI: 10.1038/s41467-022-34541-w
• EISSN: 2041-1723
• ISSN: 2041-1723
• Language: English
• Keywords: Algorithm; Limit (mathematics); Quantum information processing; Information theory; Theoretical computer science; Statistical physics; Quantum information; Computer science; Task (project management); Physics; Information processing; Computation; Quantum mechanics; Coherent information; Quantum; Entropy (arrow of time); Set (abstract data type); Quantum channel; Mathematics; Non-equilibrium thermodynamics