1995 | Lorenza Viola, Emanuel Knill, and Seth Lloyd
This paper proposes a novel method for decoupling open quantum systems from environmental interactions, enabling noise suppression while maintaining control over the system's dynamics. Open quantum systems, which interact with their environment, suffer from decoherence and dissipation, which hinder quantum information processing. The authors demonstrate that open-loop control techniques can filter out unwanted interactions and suppress noise, allowing for effective control of the system's evolution. This approach is particularly useful for quantum information processing, where maintaining quantum coherence is essential.
The method is based on the idea that no relaxation process can occur instantaneously, so control techniques must be applied faster than the fastest time scale of the environment. The authors show that by using a control algebra, one can generate a subgroup of system transformations that allow for effective dynamics while eliminating environmental effects. This leads to a general criterion for engineering noise-immune open-system evolutions.
The paper discusses the use of group-theoretical averaging to project system operators into the commutant of the control algebra, enabling maximal and selective decoupling. The effectiveness of the method is demonstrated through examples, such as a K-qubit dissipative quantum register, where decoupling can be achieved by cycling qubits through specific pulse sequences.
The results show that decoherence and decay can be suppressed in the limit of infinitesimally short control times. However, in practice, the physical requirement for decoupling is that the control time must be much shorter than the characteristic memory time of the environment. The paper also discusses the implications of this method for quantum computing, where fault-tolerant control is essential.
The authors conclude that their method provides a framework for designing effective open-system evolutions, with potential applications in quantum information processing, quantum computing, and quantum communication. The work is supported by various funding agencies and highlights the importance of decoupling techniques in overcoming the challenges of open quantum systems.This paper proposes a novel method for decoupling open quantum systems from environmental interactions, enabling noise suppression while maintaining control over the system's dynamics. Open quantum systems, which interact with their environment, suffer from decoherence and dissipation, which hinder quantum information processing. The authors demonstrate that open-loop control techniques can filter out unwanted interactions and suppress noise, allowing for effective control of the system's evolution. This approach is particularly useful for quantum information processing, where maintaining quantum coherence is essential.
The method is based on the idea that no relaxation process can occur instantaneously, so control techniques must be applied faster than the fastest time scale of the environment. The authors show that by using a control algebra, one can generate a subgroup of system transformations that allow for effective dynamics while eliminating environmental effects. This leads to a general criterion for engineering noise-immune open-system evolutions.
The paper discusses the use of group-theoretical averaging to project system operators into the commutant of the control algebra, enabling maximal and selective decoupling. The effectiveness of the method is demonstrated through examples, such as a K-qubit dissipative quantum register, where decoupling can be achieved by cycling qubits through specific pulse sequences.
The results show that decoherence and decay can be suppressed in the limit of infinitesimally short control times. However, in practice, the physical requirement for decoupling is that the control time must be much shorter than the characteristic memory time of the environment. The paper also discusses the implications of this method for quantum computing, where fault-tolerant control is essential.
The authors conclude that their method provides a framework for designing effective open-system evolutions, with potential applications in quantum information processing, quantum computing, and quantum communication. The work is supported by various funding agencies and highlights the importance of decoupling techniques in overcoming the challenges of open quantum systems.