Das Alter in der Literatur

Kiesel, Helmuth

doi:10.1007/978-3-540-76711-4_12

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…We consider two oscillators of spherical shape with uniform density ρ and radius R, which are separated by a distance L = 2.1R. This might be a situation matching current experiments in levitated optomechanics [29,30], which are rapidly evolving towards the possibility of trapping multiple dielectric nano-spheres in common optical traps and controlling their relative positions [31]. However, low-frequency oscillators, which are favourable for the figure of merit and typically associated with large masses, are unsuited to such platforms and would require a different arrangement, such as LIGO-like ones [19].…”

Section: Encompass the Variances And Correlations Of The Elements Of mentioning

confidence: 97%

Observable quantum entanglement due to gravity

et al. 2020

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No experiment to date provided evidence for quantum features of the gravitational interaction. Recently proposed tests suggest looking for the generation of quantum entanglement between massive objects as a possible route towards the observation of such features. Motivated by advances in optical cooling of mirrors, here we provide systematic study of entanglement between two masses that are coupled gravitationally. We first consider the masses trapped at all times in harmonic potentials (optomechanics) and then masses released from the traps. This leads to the estimate of the experimental parameters required for the observation of gravitationally-induced entanglement. The optomechanical setup demands LIGO-like mirrors and squeezing or long coherence times, but the released masses can be light and accumulate detectable entanglement in a timescale shorter than their decoherence times. No macroscopic quantum superposition develops during the evolution. We discuss the implications from such thought experiments regarding the nature of the gravitational coupling.arXiv:1906.08808v1 [quant-ph]

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Section: Encompass the Variances And Correlations Of The Elements Of mentioning

confidence: 97%

Observable quantum entanglement due to gravity

et al. 2020

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“…Since stability is indispensable in multi-photon experiments we replace (phase-dependent) single-photon interferometers for different polarizations by a polarization dependent (but phase-independent) two-photon interference [9]. It is well known, that in two-photon interference both photons leave the same output of the beam splitter [10].…”

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confidence: 99%

Experimental Analysis of a Four-Qubit Photon Cluster State

et al. 2005

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Linear optics quantum logic operations enabled the observation of a four-photon cluster state. We prove genuine four-partite entanglement and study its persistency, demonstrating remarkable differences to the usual GHZ state. Efficient analysis tools are introduced in the experiment, which will be of great importance in further studies on multi-particle entangled states. Multipartite entangled states play a fundamental role in the field of quantum information theory and its applications. Recently, special types of entangled multiqubit states, the so-called graph states, have moved into the center of interest [1]. Due to the fact that they can be generated by next-neighbor interactions, these states occur naturally in solid state systems or can be easily obtained in experiments on atomic lattices [2]. These graph states are basic elements of various quantum error correcting codes [3] and multi-party quantum communication protocols [4]. Well known members of this family of states are the GHZ and cluster states. The latter received a lot of attention in the context of the so-called one-way quantum computer scheme suggested by Briegel and Raussendorf [5]. There, the cluster state serves as the initial resource of a universal computation scheme based on single-qubit operations only. Very recently the principal feasibility of this approach was experimentally demonstrated for a four-photon cluster state [6].In this letter we report the experimental detection of a high fidelity four-photon cluster state. The inherent stability of the linear optics phase gate implemented here allowed a detailed characterization of the states entanglement properties as well as of its entanglement persistency under loss of qubits. Introducing stabilizer formalism [7] for the experimental analysis we were able to detect genuine four partite entanglement and to determine the states fidelity with a minimum number of measurements.The four-qubit cluster state can be written in the formwhere | H i and | V i denote linear horizontal (H) and vertical (V) polarization of a photon in the spatial mode i (i = a, b, c, d). If one compares this state with the product of two Bell states, one observes that the states are equal up to a phase factor of the last term. This phase can be generated by a controlled phase (C-Phase) gate acting on input modes This scheme directly reflects the generation principle of graph states: evidently, the state | Φ + can be generated by next-neighbor interaction, and the four-qubit cluster state is then obtained by a third interaction between the neighboring qubits b ′ and c ′ .

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“…This is actually feasible for a class of optomechanical systems where a levitated trapped object inside a cavity embodies the mechanical element [38,72,77]. Shifting the trapped position of this object with respect to the cavity field can change the strength of coupling [78,79]. We still believe that our results reflect the general case well (even when the light-mechanics coupling is present during injection) as we have modeled both phenomena separately.…”

Section: System Dynamicsmentioning

confidence: 63%

“…This can be achieved, for example, by using trapped mechanical objects as oscillators interacting with a cavity field (for which g ∼ 0.1 should be possible from the parameters of Ref. [38] by decreasing the cavity waist to 5 μm): an optically trapped object can be pushed away by a strong pulse [78]; a charged object held in a Pauli trap can be suddenly shifted relative to the cavity field by suddenly shifting the trap center [79].…”

Section: Experimental Feasibilitymentioning

confidence: 99%

Enabling entanglement distillation via optomechanics

2019

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Quantum networking based on optical Gaussian states, although promising in terms of scalability, is hindered by the fact that their entanglement cannot be distilled via Gaussian operations. We show that optomechanics, and particularly the possibility to measure the mechanical degree of freedom in an integrable system, can address this problem. Here, one of the optical modes of a two-mode squeezed vacuum is injected into a single-sided Fabry-Pérot cavity and nonlinearly coupled to a mechanical oscillator. Afterwards, the position of the oscillator is measured using pulsed optomechanics and homodyne detection. We show that this measurement can supply non-Gaussian entangled states frequently enough to enable scalable entanglement distillation. Moreover, it can conditionally increase the initial entanglement under an optimal radiation-pressure interaction strength, which corresponds to an effective unsharp measurement of the photon number inside the cavity. We show how the resulting entanglement enhancement can be verified by using a standard teleportation procedure.

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Das Alter in der Literatur

Cited by 6 publications

References 5 publications

Observable quantum entanglement due to gravity

Observable quantum entanglement due to gravity

Experimental Analysis of a Four-Qubit Photon Cluster State

Enabling entanglement distillation via optomechanics

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