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Rev. Mod. Phys.:Protecting quantum information against environmental noise

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Colloquium: Protecting quantum information against environmental noise

Dieter Suter and Gonzalo A. Álvarez
Rev. Mod. Phys. 88, 041001 (2016)
Published 10 October 2016

RevModPhys.88.041001Quantum-mechanical systems retain their properties so long as the phase of quantum superpositions evolve stably over time. Contact with an environment can disrupt this phase evolution. But for environments that do not exchange energy with the quantum system, strategies exist where the controlled driving of the system can recover or maintain the quantum phase. This Colloquium surveys the host of techniques that are available to “refocus” the phase when disturbed by various forms of classical or quantum environment. While the first such techniques were developed long ago, ideas from quantum information theory have introduced new strategies for accomplishing this goal.

Source: Reviews of Modern Physics – Volume 88 Issue 4

Experimental protection of quantum gates against decoherence and control errors | Phys. Rev. A 86, 050301(R) 2012

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 Experimental protection of quantum gates against decoherence and control errors

Alexandre M. Souza, Gonzalo A. Álvarez, and Dieter Suter
Fakultät Physik, Technische Universität Dortmund, D-44221, Dortmund, Germany

One of the biggest challenges for implementing quantum devices is the requirement to perform accurate quantum gates. The destructive effects of interactions with the environment present some of the most difficult obstacles that must be overcome for precise quantum control. In this work we implement a proof of principle experiment of quantum gates protected against a fluctuating environment and control pulse errors using dynamical decoupling techniques. We show that decoherence can be reduced during the application of quantum gates. High-fidelity quantum gates can be achieved even if the gate time exceeds the free evolution decoherence time by one order of magnitude and for protected operations consisting of up to 330 individual control pulses.

©2012 American Physical Society

via Phys. Rev. A 86, 050301 2012: Experimental protection of quantum gates against decoherence and control errors.

Gate fidelity as a function of gate time for different gate operations protected by different dynamical decoupling (DD) sequences. “Simple” indicates gates that were implemented by unprotected rotations. BB1 means that the gates are only protected by BB1 composite pulses which does not protect against decoherence. The delay between the pulses for the NOOP was ≈ 3μs.
Gate fidelity as a function of gate time for different gate operations protected by different dynamical decoupling (DD) sequences. “Simple” indicates gates that were implemented by unprotected rotations. BB1 means that the gates are only protected by BB1 composite pulses which does not protect against decoherence. The delay between the pulses for the NOOP was ≈ 3μs.