Various Couplings in Quantum Systems

Ranabir Das, Rangeet Bhattacharyya, Anil Kumar

Dipolar couplings among spin‐1/2 nuclei are long‐range and have the potential to yield large mutually‐coupled spin‐systems for quantum information processing. An eight spin dipolar coupled system is investigated for building quantum processors. Transitions between various states are identified and complete energy‐level diagram of the system is constructed with the help of a HET‐Z‐COSY spectrum. Transition selective pulses have been used to implement various controlled operations. Preparation of pseudopure states and implementation of controlled‐NOT and controlled‐SWAP gates are demonstrated.

Amjad Sohail, Jia‐Xin Peng, Abdelkader Hidki +2 more

We theoretically propose a scheme to generate distant bipartite entanglement between various subsystems in coupled magnomechanical systems where both the microwave cavities are coupled through single photon hopping coupling strength Γ. Each cavity contains a magnon mode and phonon mode and this gives six excitation modes in our model Hamiltonian which are cavity-1 photons, cavity-2 photons, magnon and phonon in cavity-1, and magnon and phonon in cavity-2. We found that significant bipartite entanglement exists between indirectly coupled subsystems in coupled microwave cavities for an appropriate set of parameters regime. Moreover, we also obtain suitable cavity and magnon detuning parameters for a significant distant bipartite entanglement in different bipartitions. In addition, it can be seen that a single photon hopping parameter significantly affects both the degree as well as the transfer of quantum entanglement between various bipartitions. Hence, our present study related to coupled microwave cavity magnomechanical configuration will open new perspectives in coherent control of various quantum correlations including quantum state transfer among macroscopic quantum systems.

Amjad Sohail, Jia‐Xin Peng, Abdelkader Hidki +1 more

We theoretically propose a scheme to generate distant bipartite entanglement between various subsystems in coupled magnomechanical systems where both the microwave cavities are coupled through single photon hopping parameter. Each cavity also contains a magnon mode and phonon mode and this gives five excitation modes in our model Hamiltonian which are cavity-1 photons, cavity-2 photons, magnon, and phonon modes in both YIG spheres. We found that significant bipartite entanglement exists between indirectly coupled subsystems in coupled microwave cavities for an appropriate set of parameters regime. Moreover, we also obtain suitable cavity and magnon detuning parameters for a significant distant bipartite entanglement in different bipartitions. In addition, it can be seen that a single photon hopping parameter significantly affects both the degree as well as the transfer of quantum entanglement between various bipartitions. Hence, our present study related to coupled microwave cavity magnomechanical configuration will open new perspectives in coherent control of various quantum correlations including quantum state transfer among macroscopic quantum systems

P. K. Shukla, Bengt Eliasson