Summary form only given. Quantum teleportation allows to transfer the quantum state of a particle to a remote location without sending the particle itself. This makes it a versatile tool for the distribution of quantum states over long distances or the remote preparation of quantum memories as they are necessary in various scenarios of quantum information processing and quantum communication. In this context atomic systems are often discussed as promising candidates for the storage and manipulation of qubit states whereas photonic qubit states are easy to prepare and to distribute. Hybrid systems of entangled atom-photon pairs can serve as an interface between those different carriers of quantum information. We utilize this property to perform teleportation of the polarization state of an attenuated laser pulse onto a single atom over a distance of 20m.Our experimental sequence consists of two steps. First the spin state of the single atom is entangled with the polarization state of a single photon in a spontaneous emission process [1]. The single photon is then sent to a second laboratory 20m away where an attenuated laser pulse with a well defined polarization state |Ψ) is prepared. In a second step a Bell-state measurement on the joint polarization state of the single photon from the atom and the attenuated laser pulse is performed (Fig. 1a). This is done via interference of the photon and the pulse at a fiber beam-splitter and subsequent coincidence detection of photons at the outputs of the beam-splitter (Fig. 1b). This teleports the input state |Ψ) onto the atom - up to a unitary tranformation depending on the outcome of the Bell-state measurement.need to be indistinguishable in all degrees of freedom except for their polarization. In particular, the temporal shape of the pulse was matched to that of the single photon using an arbitrary waveform generator and an AOM in a closed-loop feedback control. We performed this experiment with input states |Ψ) = |H), |+45°) and |R) and evaluated the fidelity to find the atom in the correspondig output state. For |+45°) and |R) the fraction of coherent pulses containing two or more photons can cause the same signal as expected from a successful Bell-state projection which reduces the overall fidelity to 0.81 and 0.84, respectively. However, for |H) the fidelty is practically only limited by the precision of the atomic state readout and reaches a value of 0.93.
Summary form only given. Quantum teleportation allows to transfer the quantum state of a particle to a remote location without sending the particle itself. This makes it a versatile tool for the distribution of quantum states over long distances or the remote preparation of quantum memories as they are necessary in various scenarios of quantum information processing and quantum communication. In this context atomic systems are often discussed as promising candidates for the storage and manipulation of qubit states whereas photonic qubit states are easy to prepare and to distribute. Hybrid systems of entangled atom-photon pairs can serve as an interface between those different carriers of quantum information. We utilize this property to perform teleportation of the polarization state of an attenuated laser pulse onto a single atom over a distance of 20m.Our experimental sequence consists of two steps. First the spin state of the single atom is entangled with the polarization state of a single photon in a spontaneous emission process [1]. The single photon is then sent to a second laboratory 20m away where an attenuated laser pulse with a well defined polarization state |Ψ) is prepared. In a second step a Bell-state measurement on the joint polarization state of the single photon from the atom and the attenuated laser pulse is performed (Fig. 1a). This is done via interference of the photon and the pulse at a fiber beam-splitter and subsequent coincidence detection of photons at the outputs of the beam-splitter (Fig. 1b). This teleports the input state |Ψ) onto the atom - up to a unitary tranformation depending on the outcome of the Bell-state measurement.need to be indistinguishable in all degrees of freedom except for their polarization. In particular, the temporal shape of the pulse was matched to that of the single photon using an arbitrary waveform generator and an AOM in a closed-loop feedback control. We performed this experiment with input states |Ψ) = |H), |+45°) and |R) and evaluated the fidelity to find the atom in the correspondig output state. For |+45°) and |R) the fraction of coherent pulses containing two or more photons can cause the same signal as expected from a successful Bell-state projection which reduces the overall fidelity to 0.81 and 0.84, respectively. However, for |H) the fidelty is practically only limited by the precision of the atomic state readout and reaches a value of 0.93.
Institute of Quantum Optics — Teleportation is a prerequisite for the transfer of quantum information over large distances when the losses inherent in any quantum channel preclude a direct transfer. We demonstrate teleportation between two single-atom quantum memories in distant laboratories. By implementing a timeresolved photonic Bell-state measurement (BSM), which is based on two-photon quantum inference, we achieve a teleportation fidelity of 88 %, largely determined by our entanglement fidelity. The problem of limited photon collection efficiency in free space is overcome by trapping each atom in an optical cavity. Compared to previous experiments with remote single material qubits, our approach boosts the overall efficiency by almost five orders of magnitude. This results in success probabilities not predominantly limited by the photon generation and collection efficiency but by the transmission and detection losses inherent in the photonic BSM.
The science fiction depiction of teleportation refers to the transfer of matter between two spatially separated spaces without the transfer of information. This largely differs from the concept of quantum teleportation, one of the most exciting concepts in modern quantum theory, though often misunderstood.1 The key difference between the sci-fi portrayal and quantum teleportation is that information is transferred between two spatially separated parties, rather than a direct transfer of matter. Applications may include quantum key distribution and quantum cryptography. At the heart of such teleportation is the phenomenon of quantum entanglement, in which the quantum state corresponding to non-local particles cannot be described independently. Sender (Alice) and receiver (Bob) share a pair of particles that are entangled. Alice performs a set of measurements (known as the Bell states analysis) on the state of her particle and that of a third particle (Charlie)—the particle whose state should be teleported to Bob. Based on the outcome of her measurements, Alice sends a signal to Bob. Bob applies a set of unitary transformations, without knowing the state, to the state of his particle. After these transformations, the state of Bob’s particle is identical to Charlie’s. Note that, during this process, Alice and Bob have no information about the state of Charlie’s particle. This process is probabilistic when implemented with entangled photons and linear optics,2 and means that sometimes Alice’s measurement outcome—that of two particles’ Bell states analysis—is not determined. Thus, Bob does not receive any classical signal, and the teleportation fails. Nevertheless, when Bob receives the signal from Alice, the state is the correct one, and teleportation has succeeded with a 100% fidelity. We can use a single particle possessing two different quantum properties to present a non-separable state, where Figure 1. (a) The setup for remote-hybrid-teleportation of photons from the spin to the orbital-angular-momentum degree of freedom (OAM DOF). A UV laser pumps a barium borate (BBO) crystal to generate photon pairs that are entangled in their OAM DOF. A polarizing Sagnac interferometer containing a dove prism (PSI-DP), shown in the inset, in combination with the half-wave plate (H), spatial light modulator (SLM), bandpass interference filter (IF) and single mode optical fiber (SMF) perform the single photon spin-OAM non-separable Bell state measurement.4 The photons couple via a fiber coupler (FC) into the SMF for detection by an avalanche photodiode (APD). The APD triggers the intensified charge-coupled camera (ICCD) to record the spatial distribution of photon B. During the preparation and measurement of photon A, photon B propagates in the delay line (D), compensating for electronic delay. (b) First and second columns show the polarization (SAM) state of C and the OAM state of the teleported photon to B. jLi, jH i, and jV i: left, horizontal, and vertical polarization, respectively. M: Mirror. PBS: Polarizing beam splitter. TEM: Transverse electromagnetic mode—this refers to the fundamental transverse mode (beam with a Gaussian profile). Q: Quarter-wave plate.
Quantum teleportation and quantum memory are two crucial elements for large-scale quantum networks. With the help of prior distributed entanglement as a "quantum channel," quantum teleportation provides an intriguing means to faithfully transfer quantum states among distant locations without actual transmission of the physical carriers [Bennett CH, et al. (1993) Phys Rev Lett 70(13):1895-1899]. Quantum memory enables controlled storage and retrieval of fast-flying photonic quantum bits with stationary matter systems, which is essential to achieve the scalability required for large-scale quantum networks. Combining these two capabilities, here we realize quantum teleportation between two remote atomic-ensemble quantum memory nodes, each composed of ∼10(8) rubidium atoms and connected by a 150-m optical fiber. The spin wave state of one atomic ensemble is mapped to a propagating photon and subjected to Bell state measurements with another single photon that is entangled with the spin wave state of the other ensemble. Two-photon detection events herald the success of teleportation with an average fidelity of 88(7)%. Besides its fundamental interest as a teleportation between two remote macroscopic objects, our technique may be useful for quantum information transfer between different nodes in quantum networks and distributed quantum computing.
Quantum teleportation provides a "disembodied" way to transfer quantum states from one object to another at a distant location, assisted by priorly shared entangled states and a classical communication channel. In addition to its fundamental interest, teleportation has been recognized as an important element in long-distance quantum communication, distributed quantum networks and measurement-based quantum computation. There have been numerous demonstrations of teleportation in different physical systems such as photons, atoms, ions, electrons, and superconducting circuits. Yet, all the previous experiments were limited to teleportation of one degree of freedom (DoF) only. However, a single quantum particle can naturally possess various DoFs -- internal and external -- and with coherent coupling among them. A fundamental open challenge is to simultaneously teleport multiple DoFs, which is necessary to fully describe a quantum particle, thereby truly teleporting it intactly. Here, we demonstrate the first teleportation of the composite quantum states of a single photon encoded in both the spin and orbital angular momentum. We develop a method to project and discriminate hyper-entangled Bell states exploiting probabilistic quantum non-demolition measurement, which can be extended to more DoFs. We verify the teleportation for both spin-orbit product states and hybrid entangled state, and achieve a teleportation fidelity ranging from 0.57 to 0.68, above the classical limit. Our work moves a step toward teleportation of more complex quantum systems, and demonstrates an enhanced capability for scalable quantum technologies.
Quantum teleportation [1] is a cornerstone of quantum information science due to its essential role in several important tasks such as the long-distance transmission of quantum information using quantum repeaters [2–4]. In this context, a challenge of paramount importance is the distribution of entanglement between remote nodes, and to use this entanglement as a resource for long-distance light-to-matter quantum teleportation. We report on the demonstration of quantum teleportation of the polarization state of a telecom-wavelength photon onto the state of a solid-state quantum memory. Entanglement is established between a rare-earth-ion doped crystal storing a single photon that is polarization-entangled with a flying telecom-wavelength photon [5, 6]. The latter is jointly measured, using highly efficient superconducting WSi nanowire single-photon detectors [7], with another flying qubit carrying the polarization state to be teleported, which heralds the teleportation. The fidelity of the polarization state of the photon retrieved from the memory is shown to be greater than the maximum fidelity achievable without entanglement, even when the combined distances travelled by the two flying qubits is 25 km of standard optical fibre. This light-to-matter teleportation channel paves the way towards long-distance implementations of quantum networks with solid-state quantum memories.
Faithful long-distance quantum teleportation necessitates prior entanglement distribution between two communicated locations. The particle carrying on the unknown quantum information is then combined with one particle of the entangled states for Bell-state measurements, which leads to a transfer of the original quantum information onto the other particle of the entangled states. However in most of the implemented teleportation experiments nowadays, the Bell-state measurements are performed even before successful distribution of entanglement. This leads to an instant collapse of the quantum state for the transmitted particle, which is actually a single-particle transmission thereafter. Thus the true distance for quantum teleportation is, in fact, only in a level of meters. In the present experiment we design a novel scheme which has overcome this limit by utilizing fiber as quantum memory. A complete quantum teleportation is achieved upon successful entanglement distribution over 967 meters in public free space. Active feed-forward control techniques are developed for real-time transfer of quantum information. The overall experimental fidelities for teleported states are better than 89.6%, which signify high-quality teleportation.