Experimental investigation of continuous-variable quantum teleportation

Abstract

We report the experimental demonstration of quantum teleportation of the quadrature amplitudes of a light field. Our experiment was stably locked for long periods, and was analyzed in terms of fidelity, F; and with signal transfer, Tq = T + + T − , and noise correlation, Vq = V + in|out V − in|out . We observed an optimum fidelity of 0.64 ± 0.02, Tq = 1.06 ± 0.02 and Vq = 0.96 ± 0.10. We discuss the significance of both Tq > 1 and Vq < 1 and their relation to the teleportation no-cloning limit. PACS numbers: 42.50Dv, 42.65Yj, 03.67Hk, 03.65Ud Quantum teleportation [1] is a key quantum information technology both in terms of communicating [2] and processing [3] quantum information. Experimental demonstrations of teleportation have so far fallen into three main categories: teleportation of photon states [4]; of ensemble properties in liquid NMR [5]; and of optical field states [6]. An important feature of the technique used in the optical field state experiment of Furusawa et al. [6] is its high efficiency. This results in the ability to faithfully teleport arbitrary input states continuously. This is due to the in principle ability to perform the required joint measurements exactly and the technical maturity of optical field detection. In contrast, the efficiency of single photon experiments is presently restricted in principle due to the inability to identify all four Bell states, and also in practice by the low efficiency of single photon production and detection.Since the Furusawa et al. experiment there have been many proposals for how quantum teleportation may be repeated using different systems [7,8,9]; applied to different input states [10,11]; generalized to multi-party situations [12]; and more comprehensively characterized [13,14]. In spite of the considerable interest, to date no new experiment has been performed [15]. This paper reports the quantum teleportation of the quadrature amplitudes of a light beam. Our scheme has a number of notable differences to the previously published experiment. The input and output states are both analyzed by the same homodyne detector, allowing a more consistent evaluation of their properties. Our experiment is based on a Nd:YAG laser that produces two squeezed beams in two independently pumped optical parametric amplifiers (OPAs). We use a more compact configuration for Alice's measurements. Finally, the encoding and decoding of the input and output signals using a total of 4 independent modulators. This allows us to completely span the phase space of the input state.We analyze our results using the fidelity, F , between the input and output states, and also with signal transfer (T q ) and noise correlation (V q ) in a manner analogous to QND analysis [7] (which we refer to as the T-V measure henceforth). This enables us to give a more detailed characterization of the performance of our teleporter.Teleportation is usually described as the disembodied transportation of an unknown quantum state from one place (Alice) to another (Bob). In our experiment, as in ref.[6],...

Efficient many-party controlled teleportation of multiqubit quantum information via entanglement

“…Theoretically, since the work of Bennett et al [1] on teleporting a qubit of unknown information with the aid of Einstein-PodolskyRosen (EPR) correlation, quantum teleportation has been extended from discrete-variable systems to continuous-variable systems [2][3][4][5] and also from a single qubit to multiqubits [6][7][8][9]. On the other hand, recent experiments have demonstrated quantum teleportation with photon-polarized states [10], optical coherent states [11], and nuclear magnetic resonance [12].…”

Experimental demonstration of quantum teleportation of a squeezed state

“…The initial approaches using qubits [1,2] have been extended to a continuous-variable (CV) system [3,4] employing the Einstein-Podolsky-Rosen (EPR) correlation [5]. So far several experiments for CVs have been demonstrated for a coherent state input using quadrature-phase amplitudes of an electromagnetic field mode [6,7,8,9]. Teleportation of quantum entanglement, i.e., entanglement swapping has been also realized [9,10].…”

Quantum Up-Conversion of Squeezed Vacuum States from 1550 to 532 nm

“…The coherences between them give rise to a squeezed photon counting noise in a balanced homodyne detector. These states have been used for the realization of teleportation [3,4], superpositions of coherent states (Schrödinger kitten states) [5,6], and quantum key distribution [7,8], as well as quantum enhancements of spectroscopy [9], imaging [10,11], and weak-force measurements such as those performed in gravitationalwave detectors [12][13][14][15]. The absence of any bright carrier field makes squeezed vacuum states ideal for quantum communication and metrology since photon-phonon scattering from the carrier field (Brillouin scattering) easily spoils the squeezed vacuum states in the audio-and radiofrequency sideband [16,17].…”