Control and Measurement of Three-Qubit Entangled States

Roos, C. F.; Riebe, M.; Häffner, Hartmut; Hänsel, Wolfgang; Benhelm, J.; Lancaster, G. P. T.; Becher, Christoph; Schmidt-Kaler, F.; Blatt, R.

doi:10.1126/science.1097522

Cited by 340 publications

(231 citation statements)

References 17 publications

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“…Of particular interest in this context is the preparation of entangled states, indispensable for quantum information processing. Notwithstanding the considerable number of experiments carried out on the generation of entanglement [14,15,16,17,18], and the effort to protect the system against undesirable imperfections and interactions, entanglement decay due to uncontrolled coupling with the environment remains a major problem yet to overcome [19,20,21]. In this scenario, quantum feedback emerges as a possible route to develop strategies to circumvent entanglement deterioration.…”

Section: Introductionmentioning

confidence: 99%

Controlling entanglement by direct quantum feedback

2008

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We discuss the generation of entanglement between electronic states of two atoms in a cavity using direct quantum feedback schemes. We compare the effects of different control Hamiltonians and detection processes in the performance of entanglement production and show that the quantumjump-based feedback proposed by us in Phys. Rev. A 76 010301(R) (2007) can protect highly entangled states against decoherence. We provide analytical results that explain the robustness of jump feedback, and also analyse the perspectives of experimental implementation by scrutinising the effects of imperfections and approximations in our model.

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Section: Introductionmentioning

confidence: 99%

Controlling entanglement by direct quantum feedback

2008

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“…Starting with two-qubit gate operations [2,3], long lived two-qubit entanglement [4,5,6], teleportation experiments [7,8], and different sorts of multi-qubit entangled states [9,10,4,11], the record for qubit-entanglement is currently presented in a 6-qubit cat state and a 8-qubit W-state [12,13]. Future improvement is expected using the technique of segmented linear Paul traps which allow to shuttle ions from a "processor" unit to a "memory" section [14].…”

Section: Introductionmentioning

confidence: 99%

Optimization of segmented linear Paul traps and transport of stored particles

Schulz

Poschinger

Singer³

et al. 2006

Fortschritte der Physik

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Single ions held in linear Paul traps are promising candidates for a future quantum computer. Here, we discuss a two-layer microstructured segmented linear ion trap. The radial and axial potentials are obtained from numeric field simulations and the geometry of the trap is optimized. As the trap electrodes are segmented in the axial direction, the trap allows the transport of ions between different spatial regions. Starting with realistic numerically obtained axial potentials, we optimize the transport of an ion such that the motional degrees of freedom are not excited, even though the transport speed far exceeds the adiabatic regime. In our optimization we achieve a transport within roughly two oscillation periods in the axial trap potential compared to typical adiabatic transports that take of the order 10 2 oscillations. Furthermore heating due to quantum mechanical effects is estimated and suppression strategies are proposed.

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“…1) 6 . For an increasing ion number, however, the initialization of the quantum register becomes more and more difficult as imperfections -like optical pumping-add up for each ion.…”

mentioning

confidence: 99%

Scalable multiparticle entanglement of trapped ions

Häffner

Hänsel²,

Roos

et al. 2005

Nature

1,144

1,134

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Entanglement, its generation, manipulation and fundamental understanding is at the very heart of quantum mechanics. The phrase entanglement was coined by Erwin Schrödinger in 1935 for particles that are described by a common wave function where individual particles are not independent of each other but where their quantum properties are inextricably interwoven 1 . Entanglement properties of two and three particles have been studied extensively and are very well understood. Entanglement of four 2 and five 3 particles was demonstrated experimentally. However, both creation and characterization of entanglement become exceedingly difficult for multi-particle systems. Thus the availability of such multiparticle entangled states together with the full information on these states in form of their 1

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Control and Measurement of Three-Qubit Entangled States

Cited by 340 publications

References 17 publications

Controlling entanglement by direct quantum feedback

Controlling entanglement by direct quantum feedback

Optimization of segmented linear Paul traps and transport of stored particles

Scalable multiparticle entanglement of trapped ions

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