## Fidelity for states of two $$\mathrm{spin-}\frac{1}{2}$$ particles in moving frames.(English)Zbl 1171.81342

Summary: Fidelity for the spin part of states of two spin-$$\frac{1}{2}$$ particles is investigated from the viewpoint of moving observers. Using a numerical approach, the behavior of the fidelity in terms of the boost parameter is described for different amounts of spin entanglement and momentum entanglement. It is shown that for the spin entangled states the fidelity decreases less than that of the case of spin product states and there are special cases for which the fidelity remains perfect regardless of moving observers’ velocity. Generally, in the limit of boosts with speeds close to the speed of light, the fidelity saturates, i.e., it reaches to a constant value that depends on the amount of momentum entanglement and the width of the momentum distribution function.

### MSC:

 81P68 Quantum computation 70H40 Relativistic dynamics for problems in Hamiltonian and Lagrangian mechanics 83A05 Special relativity 94A40 Channel models (including quantum) in information and communication theory
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### References:

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