We propose two different schemes for probabilistic implementing a non-local multiple qubits controlled-not operation via partially entangled quantum channels. The overall physical resources required for accomplishing these schemes are different and the successful implementation probabilities are also different.
We show how a non-local quantum controlled-NOT (CNOT) gate with multiple targets can be implemented with unit fidelity and unit probability. The explicit quantum circuit for implementing the operation is presented. Two schemes for probabilistic implementing the operation via partially entangled quantum channels with unit fidelity are put forward. The overall physical resources required for accomplishing these schemes are different, and the successful implementation probabilities are also different.
We propose a protocol for implementation of nonlocal CNOT operation using a partially entangled channel and show that when partially entangled pairs are taken as quantum channels, the nonlocal CNOT operation can be implemented probabilistically by introducing a collective unitary transformation. The required resources for implementation of the nonlocal CNOT operation in this case are discussed. We also point out that the nonlocal CNOT operation can be used as a puritlcation protocol to concentrate entanglement from an ensemble of partially entangled particles into a subensemble of maximally entanglement ones.
We investigate the controlled implementation of a non-local CNOT operation using a three-qubit entangled state. Firstly, we show how the non-local CNOT operation can be implemented with unit fidelity and unit probability by using a maximally entangled GHZ state as controlled quantum channel. Then, we put forward two schemes for conclusively implementing the non-local operation with unit fidelity by employing a partially entangled pure GHZ state as quantum channel. The feature of these schemes is that a third side is included, who may participate the process of quantum non-local implementation as a supervisor. Furthermore, when the quantum channel is partially entangled, the third one can rectify the state distorted by imperfect quantum channel. In addition to the GHZ class state, the W class state can also be used to implement the same non-local operation probabilistically. The probability of successful implementation using the W class state is always less than that using the GHZ class state.
We propose a protocol for implementation of nonlocal CNOT operation using a partially entangled channel and show that when partially entangled pairs are taken as quantum channels, the nonlocal CNOT operation can be implemented probabilistically by introducing a collective unitary transformation. The required resources for implementation of the nonlocal CNOT operation in this case are discussed. We also point out that the nonlocal CNOT operation can be used as a purification protocol to concentrate entanglement from an ensemble of partially entangled particles into a subensemble of maximally entanglement ones.
We present two optimal schemes for non-local implementing a single-qubit rotation operation via a maxi-mally entangled quantum channel. We report on the quantitative relations between the quantum action,entangled and classical communication resources required in the implementation. We also put forward twoschemes for conclusive implementing the non-local quantum single-qubit rotation via a partially entangledquantum channel. Both these methods can appropriately be referred to as qubit-assisted processes.
We show how a non-local quantum CNOT with (N-1)-target operation can be implemented with unit fidelity and unit probability by using a N-qubit maximally entangled GHZ state as quantum channel. We also put forward two schemes for probabilistic implementing the operation with unit fidelity by employing a partially entangled pure GHZ state as quantum channel. The overall physical resources required for accomplishing these schemes are different, and the successful implementation probabilities are also different. We also point out the non-local CNOT with (N-1)-target operation can be used as a purification protocol to concentrate entanglement from an ensemble of partially entangled GHZ states into a subensemble of maximally entangled ones.