Journal Article

Quantum teleportation of multiple degrees of freedom of a single photon

Chen, Ming-Cheng, Li, Li, Wu, Dian, Su, Zu-En, Pan, Jian-Wei, Cai, Xin-Dong, Liu, Nai-Le, Wang, Xi-Lin, Lu, Chao-Yang

2015

Overview

The quantum teleportation of composite quantum states of a single photon encoded in both spin and orbital angular momentum is achieved, with a teleportation fidelity above the classical limit, by quantum non-demolition measurement assisted discrimination of the Bell states describing the entanglement of the two degrees of freedom. Quantum teleportation of two states of one photon In the process known as quantum teleportation, quantum information encoded in a quantum particle, for example a photon, is transferred from one place to the other without ever moving the photon. Although quantum teleportation has been demonstrated with a variety of different systems, all have so far been limited in one crucial aspect: they only allow teleporting one degree of freedom. Here, Nai-Le Liu and colleagues demonstrate quantum teleportation of two degrees of freedom — spin and orbital angular momentum — in a single photon. Their experimental implementation is very complex and entails various innovative techniques, most notably a hybrid Bell-state measurement scheme. The intricacy of this scheme illustrates how difficult it will be to implement quantum teleportation of more complex quantum systems with more degrees of freedom. But this work represents a first and significant step in this direction. Quantum teleportation 1 provides a ‘disembodied’ way to transfer quantum states from one object to another at a distant location, assisted by previously shared entangled states and a classical communication channel. As well as being of fundamental interest, teleportation has been recognized as an important element in long-distance quantum communication 2 , distributed quantum networks 3 and measurement-based quantum computation 4 , 5 . There have been numerous demonstrations of teleportation in different physical systems such as photons 6 , 7 , 8 , atoms 9 , ions 10 , 11 , electrons 12 and superconducting circuits 13 . All the previous experiments were limited to the teleportation of one degree of freedom only. However, a single quantum particle can naturally possess various degrees of freedom—internal and external—and with coherent coupling among them. A fundamental open challenge is to teleport multiple degrees of freedom simultaneously, which is necessary to describe a quantum particle fully and, therefore, to teleport it intact. Here we demonstrate quantum teleportation of the composite quantum states of a single photon encoded in both spin and orbital angular momentum. We use photon pairs entangled in both degrees of freedom (that is, hyper-entangled) as the quantum channel for teleportation, and develop a method to project and discriminate hyper-entangled Bell states by exploiting probabilistic quantum non-demolition measurement, which can be extended to more degrees of freedom. We verify the teleportation for both spin–orbit product states and hybrid entangled states, and achieve a teleportation fidelity ranging from 0.57 to 0.68, above the classical limit. Our work is a step towards the teleportation of more complex quantum systems, and demonstrates an increase in our technical control of scalable quantum technologies.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 132/124 / 639/766/400/482 / 639/766/483/3925 / 639/766/483/481 / Atoms & subatomic particles / Humanities and Social Sciences / letter / multidisciplinary / Observations / Photons / Quantum physics / Quantum teleportation / Science