# Improving the entanglement transfer from continuous-variable systems to localized qubits using non-Gaussian states

## Abstract

We investigate the entanglement transfer from a bipartite continuous-variable (CV) system to a pair of localized qubits assuming that each CV mode couples to one qubit via the off-resonance Jaynes-Cummings interaction with different interaction times for the two subsystems. First, we consider the case of the CV system prepared in a Bell-like superposition and investigate the conditions for maximum entanglement transfer. Then we analyze the general case of two-mode CV states that can be represented by a Schmidt decomposition in the Fock number basis. This class includes both Gaussian and non-Gaussian CV states, as, for example, twin-beam (TWB) and pair-coherent (TMC, also known as two-mode-coherent) states, respectively. Under resonance conditions, equal interaction times for both qubits and different initial preparations, we find that the entanglement transfer is more efficient for TMC than for TWB states. In the perspective of applications such as in cavity QED or with superconducting qubits, we analyze in detail the effects of off-resonance interactions (detuning) and different interaction times for the two qubits, and discuss conditions to preserve the entanglement transfer.

- Authors:

- Dipartimento di Fisica, Universita di Milano, Milano (Italy)

- Publication Date:

- OSTI Identifier:
- 20982282

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.75.032336; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; EIGENSTATES; GAUSSIAN PROCESSES; INTERACTIONS; QUANTUM COMPUTERS; QUANTUM ELECTRODYNAMICS; QUANTUM ENTANGLEMENT; QUANTUM MECHANICS; QUBITS; RESONANCE

### Citation Formats

```
Casagrande, Federico, Lulli, Alfredo, and Paris, Matteo G. A.
```*Improving the entanglement transfer from continuous-variable systems to localized qubits using non-Gaussian states*. United States: N. p., 2007.
Web. doi:10.1103/PHYSREVA.75.032336.

```
Casagrande, Federico, Lulli, Alfredo, & Paris, Matteo G. A.
```*Improving the entanglement transfer from continuous-variable systems to localized qubits using non-Gaussian states*. United States. doi:10.1103/PHYSREVA.75.032336.

```
Casagrande, Federico, Lulli, Alfredo, and Paris, Matteo G. A. Thu .
"Improving the entanglement transfer from continuous-variable systems to localized qubits using non-Gaussian states". United States.
doi:10.1103/PHYSREVA.75.032336.
```

```
@article{osti_20982282,
```

title = {Improving the entanglement transfer from continuous-variable systems to localized qubits using non-Gaussian states},

author = {Casagrande, Federico and Lulli, Alfredo and Paris, Matteo G. A.},

abstractNote = {We investigate the entanglement transfer from a bipartite continuous-variable (CV) system to a pair of localized qubits assuming that each CV mode couples to one qubit via the off-resonance Jaynes-Cummings interaction with different interaction times for the two subsystems. First, we consider the case of the CV system prepared in a Bell-like superposition and investigate the conditions for maximum entanglement transfer. Then we analyze the general case of two-mode CV states that can be represented by a Schmidt decomposition in the Fock number basis. This class includes both Gaussian and non-Gaussian CV states, as, for example, twin-beam (TWB) and pair-coherent (TMC, also known as two-mode-coherent) states, respectively. Under resonance conditions, equal interaction times for both qubits and different initial preparations, we find that the entanglement transfer is more efficient for TMC than for TWB states. In the perspective of applications such as in cavity QED or with superconducting qubits, we analyze in detail the effects of off-resonance interactions (detuning) and different interaction times for the two qubits, and discuss conditions to preserve the entanglement transfer.},

doi = {10.1103/PHYSREVA.75.032336},

journal = {Physical Review. A},

number = 3,

volume = 75,

place = {United States},

year = {Thu Mar 15 00:00:00 EDT 2007},

month = {Thu Mar 15 00:00:00 EDT 2007}

}