Abstract We evaluate a one-way, bidirectional, and cyclic quantum controlled teleportation with two controllers. We show that the controllers’ agreement mimics the OR logic gate, i.e., the teleportation succeeds with only one of the controllers’ cooperation, and it does not matter which one. This result is generalized to multi-way quantum controlled teleportation with N controllers. The proposed protocols are evaluated by considering a noisy environment in the form of phase-damping noise and amplitude-damping noise and the dependence of fidelity only on the decoherence rate and the initial state’s amplitude parameter were established. It is interesting to note that for the phase-damping noise case, there are states with perfect fidelity (and the entropy equal to zero) even in a noisy environment. We discuss the novelty of the proposed protocols and highlight that they can be useful if the information to be teleported needs an OR-logic-gate-like controllers’ agreement combination, which cannot be done with other existing protocols.
Abstract The quantum logic gate is a basic operation in quantum computing. SWAP gates are quite useful as a type of two-qubit logic gate. In this paper, we propose a fast scheme to get a deterministic SWAP gate between two atoms in just one step. In this scheme the experimental parameters, such as evolution time, laser parameters and so on, do not need to be controlled precisely. This greatly simplifies the actual operation. Meanwhile, the strict numerical simulations show that decoherence arising from spontaneous emission and cavity decay may be allowed to some extent. What is more, the idea can be used to generate a SWAP gate between two spatially separate atoms. It is worth noting that our scheme simplifies the complex steps found in some pre-existing schemes.
The theory of logical gates in quantum computation has suggested new forms of quantum logic, called quantum computational logics. The basic semantic idea is the following: the meaning of a sentence is identified with a quantum information quantity, represented by a quregister (a system of qudits) or, more generally, by a mixture of quregisters (called qumix), whose dimension depends on the logical complexity of the sentence. At the same time, the logical connectives are interpreted as logical operations defined in terms of quantum logical gates. Physical models of quantum computational logics can be built by means of Mach-Zehnder interferometers.