Optimal continuous-variable teleportation under energy constraint

Abstract

Quantum teleportation is one of the crucial protocols in quantum information processing. It is important to accomplish an efficient teleportation under practical conditions, aiming at a higher fidelity desirably using fewer resources. The continuous-variable (CV) version of quantum teleportation was first proposed using a Gaussian state as a quantum resource, while other attempts were also made to improve performance by applying non-Gaussian operations. We investigate the CV teleportation to find its ultimate fidelity under energy constraint identifying an optimal quantum state. For this purpose, we present a formalism to evaluate teleportation fidelity as an expectation value of an operator. Using this formalism, we prove that the optimal state must be a form of photon-number entangled states. We further show that Gaussian states are near-optimal while non-Gaussian states make a slight improvement and therefore are rigorously optimal, particularly in the low-energy regime.

Quantum non-Gaussianity and secure quantum communication

“…That is, under the covariant BK teleportation scheme, the output fidelity is solely determined by the correlation property of the two-mode resource state expressed in Eq. (31). This can also be used to indirectly confirm security of teleportation channel Alice and Bob possess.…”

Continuous-variable quantum teleportation through bosonic memory channel

“…Such an entangled state will be corrupted and the entanglement property is degraded since the quantum channel is embedded in the environment. Unlike the existing schemes [7][8][9][10][11], we assume the quantum channel with the memory effects. The covariance matrix of the propagating modes can be transformed accord to the relation (7).…”

“…Quantum teleportation, originally proposed in the seminal work of Bennett et al [1], has been become one of the most strikingly interesting field in quantum information science and allows for the disembodied transmission of arbitrary unknown quantum states from a sending station to a remote receiving station by utilizing shared entanglement source and classical communication. There has thus been much interest in theoretically investigating quantum teleportation in various physical systems ranging from two-qubit systems [2][3][4][5], Ndimensional systems [6], continuous-variable systems [7][8][9][10][11], and hybrid systems [12,13]. Among these, the scenarios for continuous-variable quantum teleportation have been extensively received much attention due to the high-detection efficiency and handy manipulation of continuous-variable states, and some of them have been successfully implemented in experiment.…”

Estimating Non-Gaussianity of a Quantum State by Measuring Orthogonal Quadratures

“…Non-Gaussian operations can improve nonclassical properties including optical nonclassicality [ 14 , 15 , 16 ], quantum entanglement [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ], and quantum nonlocality [ 26 , 27 , 28 , 29 ]. Moreover, they can enhance the performance of CV quantum information protocols, such as quantum teleportation [ 30 , 31 , 32 , 33 , 34 ], quantum linear amplification [ 35 , 36 , 37 ], quantum dense coding [ 38 ], quantum key distribution [ 39 ], and quantum target detection [ 40 ].…”