arXiv:0805.1432

The decoherence of coupled spin qubits system

Toshifumi Itakura

Published May 10, 2008• 0 citations

Abstract

In this report, we examine the decoherence of a spin qubits system coupled to counted spin chain with a $1/r^2$ interaction by using influence functional. We also examine the time evolution of density matrix numerically when environment is Gaussian noise.

DOI: 10.48550/arxiv.0805.1432

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arXiv:0805.1432

The decoherence of coupled spin qubits system

Toshifumi Itakura

Published May 10, 2008• 0 citations

arXiv HTML PDF

Abstract

In this report, we examine the decoherence of a spin qubits system coupled to counted spin chain with a

1/r^2

interaction by using influence functional. We also examine the time evolution of density matrix numerically when environment is Gaussian noise.

DOI: 10.48550/arxiv.0805.1432

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We study the time evolution of decoherence factor of two spin qubits and qutrits coupled to an $XY$ spin chain with Dzyaloshinsky-Moriya (DM) interaction environment. The dynamical process of the decoherence is numerically and analytically investigated. We find that the DM interaction can enhance slightly the decay of the decoherence factor in the weak-coupling region. However, in the strong-coupling region, the decoherence factor is very sensitive to the DM interaction.We study the time evolution of decoherence factor of two spin qubits and qutrits coupled to an $XY$ spin chain with Dzyaloshinsky-Moriya (DM) interaction environment. The dynamical process of the decoherence is numerically and analytically investigated. We find that the DM interaction can enhance slightly the decay of the decoherence factor in the weak-coupling region. However, in the strong-coupling region, the decoherence factor is very sensitive to the DM interaction.

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arXiv:2410.22003Physical review. B./Physical review. BApr 18, 20251 citation

In this report, we examine the decoherence of a spin qubits system coupled to counted spin chain with a

1/r^2

interaction by using influence functional. We also examine the time evolution of density matrix numerically when environment is Gaussian noise.

We study the time evolution of decoherence factor of two spin qubits and qutrits coupled to an

XY

spin chain with Dzyaloshinsky-Moriya (DM) interaction environment. The dynamical process of the decoherence is numerically and analytically investigated. We find that the DM interaction can enhance slightly the decay of the decoherence factor in the weak-coupling region. However, in the strong-coupling region, the decoherence factor is very sensitive to the DM interaction.

In this report, we examine the relaxation phenomena of a spin qubit coupled to a spin chain with a

1/r^2

interaction.

We study decoherence induced on a two-level system coupled to a one-dimensional quantum spin chain. We consider the cases where the dynamics of the chain is determined by the Ising,

XY

, or Heisenberg exchange Hamiltonian. This model of quantum baths can be of fundamental importance for the understanding of decoherence in open quantum systems, since it can be experimentally engineered by using atoms in optical lattices. As an example, here we show how to implement a pure dephasing model for a qubit system coupled to an interacting spin bath. We provide results that go beyond the case of a central spin coupled uniformly to all the spins of the bath, in particular showing what happens when the bath enters different phases, or becomes critical; we also study the dependence of the coherence loss on the number of bath spins to which the system is coupled and we describe a coupling-independent regime in which decoherence exhibits universal features, irrespective of the system-environment coupling strength. Finally, we establish a relation between decoherence and entanglement inside the bath. For the Ising and the

XY

models we are able to give an exact expression for the decay of coherences, while for the Heisenberg bath we resort to the numerical time-dependent density matrix renormalization group.

XXZ

spin chain, we observe diverse dynamics in the qubit evolution, reflecting different parameters of the chain. This demonstrates that a spin qubit can probe both quantitative properties of the spin chain and qualitative characteristics, such as the bipartite entanglement entropy, phase transitions, and perturbation propagation velocity within the system. This approach reveals the power of small quantum systems to probe the properties of large, strongly correlated quantum systems.