Optimal pulse spacing for dynamical decoupling in the presence of a purely dephasing spin bath

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.032303· OSTI ID:21537399

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

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

Maintaining quantum coherence is a crucial requirement for quantum computation; hence protecting quantum systems against their irreversible corruption due to environmental noise is an important open problem. Dynamical decoupling (DD) is an effective method for reducing decoherence with a low control overhead. It also plays an important role in quantum metrology, where, for instance, it is employed in multiparameter estimation. While a sequence of equidistant control pulses [the Carr-Purcell-Meiboom-Gill (CPMG) sequence] has been ubiquitously used for decoupling, Uhrig recently proposed that a nonequidistant pulse sequence [the Uhrig dynamic decoupling (UDD) sequence] may enhance DD performance, especially for systems where the spectral density of the environment has a sharp frequency cutoff. On the other hand, equidistant sequences outperform UDD for soft cutoffs. The relative advantage provided by UDD for intermediate regimes is not clear. In this paper, we analyze the relative DD performance in this regime experimentally, using solid-state nuclear magnetic resonance. Our system qubits are {sup 13}C nuclear spins and the environment consists of a {sup 1}H nuclear spin bath whose spectral density is close to a normal (Gaussian) distribution. We find that in the presence of such a bath, the CPMG sequence outperforms the UDD sequence. An analogy between dynamical decoupling and interference effects in optics provides an intuitive explanation as to why the CPMG sequence performs better than any nonequidistant DD sequence in the presence of this kind of environmental noise.

• OSTI ID: 21537399
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 83; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR MOMENTUM
COMPUTERS
CONTROL
DECOUPLING
FUNCTIONS
GAUSS FUNCTION
HYDROGEN 1
HYDROGEN ISOTOPES
INFORMATION
INTERFERENCE
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NOISE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
OPTICS
PARTICLE PROPERTIES
PULSES
QUANTUM COMPUTERS
QUANTUM INFORMATION
QUBITS
RESONANCE
SOLIDS
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
SPIN
STABLE ISOTOPES