Large-scale quantum computers will require quantum gate operations between widely separated qubits. A method for implementing such operations, known as quantum gate teleportation (QGT), requires only local operations, classical communication, and shared entanglement. We demonstrate QGT in a scalable architecture by deterministically teleporting a controlled-NOT (CNOT) gate between two qubits in spatially separated locations in an ion trap. The entanglement fidelity of our teleported CNOT is in the interval (0.845, 0.872) at the 95% confidence level. The implementation combines ion shuttling with individually addressed single-qubit rotations and detections, same- and mixed-species two-qubit gates, and real-time conditional operations, thereby demonstrating essential tools for scaling trapped-ion quantum computers combined in a single device.
We propose to combine neutral atom and trapped ion qubits in one scalable modular architecture that uses shuttling of individual neutral atoms in optical tweezers to realize atomic interconnects between trapped ion quantum registers. These interconnects are , and thus may be performed . The proposed protocol is as follows: A tweezer-trapped neutral atom qubit is brought close to a trapped ion in an ion chain serving as a module of a larger quantum computer, and an entangling gate is performed between the two qubits. Then, the neutral atom is quickly moved to another, nearby trapped ion chain in the same modular ion trap and entangled with an ion in that chain, thus entangling the two separate ion chains. The optical dipole potential of the tweezer beam for the neutral atom does not measurably affect the trapped ions, while the rf ion trap does not affect the neutral atom. With realistic tweezer trap parameters, the neutral atom can be moved over millimeter-scale distance in a few tens of microseconds, thus enabling a remote entanglement generation rate of over 10 3 s − 1 even with very modest assumptions for the atom-ion quantum gate speed, and possibly up to 10 4 s − 1 , which is two orders of magnitude higher than the current state-of-the-art with photonic interconnects.
Physicists in Austria and the US have shown for the first time how to teleport the properties of one atom to another. At the National Institute of Standards and Technology, a team of teleporters trapped three beryllium ions. The ions - beryllium atoms with missing electrons and hence a positive charge - are subjected to forces from electric fields so that they can be held in an ion trap. Here, radio waves and electric fields from a set of electrodes hold the ions in a line but also allow them to be moved from one segment of the trap to the other. This way, ions could be brought over to the different laser beams used for entanglement and for the measurement of quantum states. Two atoms can be entangled by simultaneously undergoing changes in quantum state when hit with a specific series of laser pulses. The same teleportation protocol was used by another team at Innsbruck University. However, this team used a different type of trap, one with no segments. Instead of moving the ions to the lasers, the team was able to aim the lasers well enough so that they could move the laser beams to the ions. These simple trap systems have been found to be very promising and may first be applied in a specialized computer called quantum repeater. This kind of device, though still the stuff of mere theory, would extend the range of wiretap-proof quantum communication systems that encode messages in the polarization of photons.