Quantum Information Processing in Artificial Molecules

Peter Rabl

Robin Côté, Susanne F. Yelin, D. DeMille

Nanjian Wu

Solomon Akpore Uriri, Yaseera Ismail, Francesco Petruccione

Metamaterials are artificially engineered periodic structures with exceptional optical properties that are not found in conventional materials. However, this definition of metamaterials can be extended if we introduce a quantum degree of freedom by adding some quantum elements (e.g quantum dots, cold atoms, Josephson junctions, molecules). Quantum metamaterials can then be defined as artificially engineered nanostructures made up of quantum elements. Furthermore, they exhibit controllable quantum states, maintain quantum coherence for times much higher than the transversal time of the electromagnetic signal. Metamaterials have been used to realised invisibility cloaking, super-resolution, energy harvesting, and sensing. Most of these applications are performed in the classical regime. Of recent, metamaterials have gradually found their way into the quantum regime, particularly to quantum sensing and quantum information processing. The use of quantum metamaterials for quantum information processing is still new and rapidly growing. In quantum information processing, quantum metamaterials have enabled the control and manipulation of quantum states, single photon generation, creating quantum entanglement, quantum states switching, quantum search algorithm, quantum state engineering tasks, and many more. In this work, we briefly review the theory, fabrication and applications of quantum metamaterials to quantum information processing.

Hamid Reza Hamedi

A novel configuration is proposed to study optical bistability (OB) and optical multistability (OM) in a superconducting quantum circuit with a tunable V-type artificial molecule constructed by two superconducting Josephson charge qubits coupled with each other through a superconducting quantum interference device. We find that the ratio of the Josephson coupling energy to the capacitive coupling strength has a significant impact on creating optical bistability. The influence of other system parameters on bistable behavior of the artificial medium is then discussed. In particular, it is found that applying an incoherent pumping field can noticeably reduce the bistable threshold. We also realize a switch from OB to OM through proper tuning of detuning parameters. The controllability of OB and OM of this artificial molecule may be useful in building logic-gate devices for optical computing and quantum information processing and provide some new possibilities for solid-state quantum information science.

Masahiro Kitagawa