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Control quantum evolution speed of a single dephasing qubit for arbitrary initial states via periodic dynamical
Ya-Ju Song1, Qing-Shou Tan2, Le-Man Kuang1
1Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha 410081, China.
Scientific Reports
|March 9, 2017
Summary
Periodic dynamical decoupling (PDD) pulses can control quantum evolution speed for dephasing qubits. PDD influences quantum speed limit time (QSLT) by modulating coherence and system non-Markovianity.
Area of Science:
- Quantum Information Science
- Quantum Control
- Quantum Computing
Background:
- Controlling quantum system dynamics is crucial for quantum technologies.
- Dephasing limits the speed and fidelity of quantum computations.
- Quantum Speed Limit Time (QSLT) quantifies the minimum time for quantum evolution.
Purpose of the Study:
- To investigate controlling quantum evolution speed of a single dephasing qubit.
- To explore the role of periodic dynamical decoupling (PDD) pulses.
- To analyze the impact of PDD on Quantum Speed Limit Time (QSLT).
Main Methods:
- Theoretical investigation of a single dephasing qubit under periodic dynamical decoupling (PDD) pulses.
- Analysis of quantum evolution speed and Quantum Speed Limit Time (QSLT).
- Consideration of a zero-temperature Ohmic-like dephasing reservoir, distinguishing between Markovian (Ohmic/sub-Ohmic) and non-Markovian (super-Ohmic) regimes.
Main Results:
- QSLT is determined by initial/final coherence and system non-Markovianity.
- PDD pulses can modulate final qubit coherence and system non-Markovianity.
- PDD can accelerate quantum evolution in the short-time regime for arbitrary initial states.
- PDD can lead to speedup or slowdown in the long-time regime.
- The effect of PDD on QSLT differs significantly between Markovian and non-Markovian reservoirs.
Conclusions:
- PDD offers a viable method for controlling quantum evolution speed and QSLT.
- The interplay between PDD, coherence, and reservoir properties is key to speed control.
- Understanding these dynamics is essential for designing robust quantum algorithms and devices.
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