Performance comparison of dynamical decoupling sequences for a qubit in a rapidly fluctuating spin bath
- 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, Journal Name: Physical Review. A Journal Issue: 4 Vol. 82; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ANGULAR MOMENTUM
BARYONS
CARBON 13
CARBON ISOTOPES
COMPARATIVE EVALUATIONS
CORRELATIONS
DECOUPLING
DIPOLES
ELEMENTARY PARTICLES
EVALUATION
EVEN-ODD NUCLEI
FERMIONS
HADRONS
HYDROGEN 1
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC DIPOLES
MECHANICS
MULTIPOLES
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
PARTICLE PROPERTIES
PERFORMANCE
PROTONS
PULSES
QUANTUM DECOHERENCE
QUANTUM INFORMATION
QUANTUM MECHANICS
QUANTUM STATES
QUBITS
SPIN
STABLE ISOTOPES