6533b82efe1ef96bd1293d4f
RESEARCH PRODUCT
Fundamental bounds on qubit reset
Christiane P. KochChristiane P. KochDaniel BasilewitschDaniel BasilewitschDaniel M. ReichDaniel M. ReichDominique SugnyJonas FischerJonas FischerJonas Fischersubject
media_common.quotation_subjectFOS: Physical sciencesQuantum controlFidelityTopology53001 natural sciences010305 fluids & plasmassymbols.namesakeComputer Science::Emerging TechnologiesDimension (vector space)0103 physical sciencesQuantum information architectures & platformsQuantum information010306 general physicsQuantum information architectures & platformsmedia_commonPhysicsQuantum Physics500 Naturwissenschaften und Mathematik::530 Physik::530 PhysikHilbert spaceQuantum controlQuantum PhysicsQubitsymbolsQuantum InformationQuantum Physics (quant-ph)Reset (computing)description
Qubit reset is a basic prerequisite for operating quantum devices, requiring the export of entropy. The fastest and most accurate way to reset a qubit is obtained by coupling the qubit to an ancilla on demand. Here, we derive fundamental bounds on qubit reset in terms of maximum fidelity and minimum time, assuming control over the qubit and no control over the ancilla. Using the Cartan decomposition of the Lie algebra of qubit plus two-level ancilla, we identify the types of interaction and controls for which the qubit can be purified. For these configurations, we show that a time-optimal protocol consists of purity exchange between qubit and ancilla brought into resonance, where the maximum fidelity is identical for all cases but the minimum time depends on the type of interaction and control. Furthermore, we find the maximally achievable fidelity to increase with the size of the ancilla Hilbert space, whereas the reset time remains constant.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2020-01-24 |