Using an exactly solvable pure dephasing model, we show how entanglement between qubits can be generated via the interaction with a common environment and concurrent application of suitable control pulses. The control pulses are able to effectively remove the detrimental effect of the environment while preserving the indirect interaction between the qubits, thereby leading to the generation of near-perfect entanglement. Furthermore, we also investigate the entanglement dynamics if the qubits are directly interacting; this interaction may even contain a noise term. The present of this additional noise leads to an additional decoherence term. This decoherence term cannot be removed by applying the pulses at the same time to both qubits. Rather, we show that by introducing a time delay between the two pulse sequences, near-perfect entanglement can still be generated via the interaction with the common environment.Using an exactly solvable pure dephasing model, we show how entanglement between qubits can be generated via the interaction with a common environment and concurrent application of suitable control pulses. The control pulses are able to effectively remove the detrimental effect of the environment while preserving the indirect interaction between the qubits, thereby leading to the generation of near-perfect entanglement. Furthermore, we also investigate the entanglement dynamics if the qubits are directly interacting; this interaction may even contain a noise term. The present of this additional noise leads to an additional decoherence term. This decoherence term cannot be removed by applying the pulses at the same time to both qubits. Rather, we show that by introducing a time delay between the two pulse sequences, near-perfect entanglement can still be generated via the interaction with the common environment.

arXiv:2212.04153Dec 8, 20220 citations

All (qubit) decoherences: Complete characterization and physical implementation

Mário Ziman, Vladimír Bužek

We investigate decoherence channels that are modeled as a sequence of collisions of a quantum system (e.g., a qubit) with particles (e.g., qubits) of the environment. We show that collisions induce decoherence when a bipartite interaction between the system qubit and an environment (reservoir) qubit is described by the controlled- $U$ unitary transformation (gate). We characterize decoherence channels and in the case of a qubit we specify the most general decoherence channel and derive a corresponding master equation. Finally, we analyze entanglement that is generated during the process of decoherence between the system and its environment.We investigate decoherence channels that are modeled as a sequence of collisions of a quantum system (e.g., a qubit) with particles (e.g., qubits) of the environment. We show that collisions induce decoherence when a bipartite interaction between the system qubit and an environment (reservoir) qubit is described by the controlled-$U$ unitary transformation (gate). We characterize decoherence channels and in the case of a qubit we specify the most general decoherence channel and derive a corresponding master equation. Finally, we analyze entanglement that is generated during the process of decoherence between the system and its environment.

arXiv:quant-ph/0505040Physical Review AAug 19, 2005111 citations

Decoherence of qubit entanglement caused by transient environments

Masashi Ban

Journal of Physics B Atomic Molecular and Optical PhysicsFeb 26, 20080 citations

Reducing decoherence in quantum-computer memory with all quantum bits coupling to the same environment

L.-M. Duan, Guang-Can Guo

Decoherence in quantum-computer memory due to the inevitable coupling to the external environment is examined. We make the assumption that all quantum bits (qubits) interact with the same environment rather than the assumption of separate environments for different qubits. It is found that the qubits decohere collectively. For some kinds of entangled input states, no decoherence occurs at all in the memory, even if the qubits are interacting with the environment. Based on this phenomenon, a scheme is proposed for reducing the collective decoherence. We also discuss possible implications of this decoherence model for quantum measurements.Decoherence in quantum-computer memory due to the inevitable coupling to the external environment is examined. We make the assumption that all quantum bits (qubits) interact with the same environment rather than the assumption of separate environments for different qubits. It is found that the qubits decohere collectively. For some kinds of entangled input states, no decoherence occurs at all in the memory, even if the qubits are interacting with the environment. Based on this phenomenon, a scheme is proposed for reducing the collective decoherence. We also discuss possible implications of this decoherence model for quantum measurements.

arXiv:quant-ph/9612003Physical Review AFeb 1, 1998259 citations

Entanglement dynamics of qubits in a common environment

Jun‐Hong An, Shun-Jin Wang, Hong‐Gang Luo

arXiv:quant-ph/0604020Physica A Statistical Mechanics and its ApplicationsApr 20, 200731 citations

U

unitary transformation (gate). We characterize decoherence channels and in the case of a qubit we specify the most general decoherence channel and derive a corresponding master equation. Finally, we analyze entanglement that is generated during the process of decoherence between the system and its environment.