Preparing Maximally Entangled States By Monitoring the Environment-System Interaction

A common assumption in open quantum systems in general is that the noise induced by the environment, due to the continuous interaction between a quantum system and its environment, is responsible for the disappearance of quantum properties of this quantum system. Interestingly, we show that an environment can be engineered and controlled to direct an arbitrary quantum system towards a maximally entangled state and thus can be considered as a resource for quantum information processing. Barreiro et.al. [Nature 470, 486 (2011)] demonstrated this idea experimentally using an open-system quantum simulator up to five trapped ions . In this paper, we direct an arbitrary initial mixed state of two and four qubits, which is interacting with its environment, into a maximally entangled state . We use QASM simulator and also an IBM Q real processor, with and without errors mitigating, to investigate the effect of the noise on the preparation of the initial mixed state of the qubits in addition to the population of the target state.