Performance comparison of dynamical decoupling sequences for a qubit in a rapidly fluctuating spin bath

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.82.042306· OSTI ID:21450724

Alvarez, Gonzalo A; Suter, Dieter ^[1]; Ajoy, Ashok ^[1]; Xinhua, Peng ^[1]

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1. Fakultaet Physik, Technische Universitaet Dortmund, D-44221 Dortmund (Germany)

Avoiding the loss of coherence of quantum mechanical states is an important prerequisite for quantum information processing. Dynamical decoupling (DD) is one of the most effective experimental methods for maintaining coherence, especially when one can access only the qubit system and not its environment (bath). It involves the application of pulses to the system whose net effect is a reversal of the system-environment interaction. In any real system, however, the environment is not static, and therefore the reversal of the system-environment interaction becomes imperfect if the spacing between refocusing pulses becomes comparable to or longer than the correlation time of the environment. The efficiency of the refocusing improves therefore if the spacing between the pulses is reduced. Here, we quantify the efficiency of different DD sequences in preserving different quantum states. We use {sup 13}C nuclear spins as qubits and an environment of {sup 1}H nuclear spins as the environment, which couples to the qubit via magnetic dipole-dipole couplings. Strong dipole-dipole couplings between the proton spins result in a rapidly fluctuating environment with a correlation time of the order of 100 {mu}s. Our experimental results show that short delays between the pulses yield better performance if they are compared with the bath correlation time. However, as the pulse spacing becomes shorter than the bath correlation time, an optimum is reached. For even shorter delays, the pulse imperfections dominate over the decoherence losses and cause the quantum state to decay.

• OSTI ID: 21450724
• Journal Information: Physical Review. A, Vol. 82, Issue 4; Other Information: DOI: 10.1103/PhysRevA.82.042306; (c) 2010 The American Physical Society; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON 13
COMPARATIVE EVALUATIONS
CORRELATIONS
DECOUPLING
HYDROGEN 1
MAGNETIC DIPOLES
PERFORMANCE
PROTONS
PULSES
QUANTUM DECOHERENCE
QUANTUM MECHANICS
QUANTUM STATES
QUBITS
SPIN
ANGULAR MOMENTUM
BARYONS
CARBON ISOTOPES
DIPOLES
ELEMENTARY PARTICLES
EVALUATION
EVEN-ODD NUCLEI
FERMIONS
HADRONS
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MECHANICS
MULTIPOLES
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
PARTICLE PROPERTIES
QUANTUM INFORMATION
STABLE ISOTOPES