dorsal/arxiv
View SchemaQuantum dynamics of double-qubits in a spin star lattice with an XY interaction
| Authors | Jun Jing, Zhi-Guo Lü |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0612115 |
| URL | https://arxiv.org/abs/quant-ph/0612115 |
Abstract
The dynamics of two coupled spins-1/2 interacting with a spin-bath via the quantum Heisenberg XY coupling is studied. The pair of central spins served as a quantum open subsystem are initially prepared in two types of states: the product states and the Bell states. The bath, which consists of $N$ (in the thermodynamic limit $N\to\infty$) mutually coupled spins-1/2, is in a thermal state at the beginning. By the Holstein-Primakoff transformation, the model can be treated effectively as two spin qubits embedded in a single mode cavity. The time-evolution of the purity, z-component summation and the concurrence of the central spins can be determined by a Laguerre polynomial scheme. It is found that (i) at a low temperature, the uncoupled subsystem in a product state can be entangled due to the interaction with bath, which is tested by the Peres-Horodecki separability; however, at a high temperature, the bath produces a stronger destroy effect on the purity and entanglement of the subsystem; (ii) when the coupling strength between the two central spins is large, they are protected strongly against the bath; (iii) when the interaction between the subsystem and the bath is strong, the collapse of the two spin qubits from their initial entangled state is fast.
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"abstract": "The dynamics of two coupled spins-1/2 interacting with a spin-bath via the\nquantum Heisenberg XY coupling is studied. The pair of central spins served as\na quantum open subsystem are initially prepared in two types of states: the\nproduct states and the Bell states. The bath, which consists of $N$ (in the\nthermodynamic limit $N\\to\\infty$) mutually coupled spins-1/2, is in a thermal\nstate at the beginning. By the Holstein-Primakoff transformation, the model can\nbe treated effectively as two spin qubits embedded in a single mode cavity. The\ntime-evolution of the purity, z-component summation and the concurrence of the\ncentral spins can be determined by a Laguerre polynomial scheme. It is found\nthat (i) at a low temperature, the uncoupled subsystem in a product state can\nbe entangled due to the interaction with bath, which is tested by the\nPeres-Horodecki separability; however, at a high temperature, the bath produces\na stronger destroy effect on the purity and entanglement of the subsystem; (ii)\nwhen the coupling strength between the two central spins is large, they are\nprotected strongly against the bath; (iii) when the interaction between the\nsubsystem and the bath is strong, the collapse of the two spin qubits from\ntheir initial entangled state is fast.",
"arxiv_id": "quant-ph/0612115",
"authors": [
"Jun Jing",
"Zhi-Guo L\u00fc"
],
"categories": [
"quant-ph"
],
"title": "Quantum dynamics of double-qubits in a spin star lattice with an XY interaction",
"url": "https://arxiv.org/abs/quant-ph/0612115"
},
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