We study a generalized coupling system between a superconducting qubit and two nanomechanical resonators. When the eigenfrequency of the superconducting qubit is twice the frequency of the resonators, we show that one qubit is able to excite simultaneously two resonators. Moreover, tripartite and bipartite macroscopic entangled states are generated, respectively. We give conditions under which general tripartite and bipartite entangled nonorthogonal states become maximally entangled states. Under a large detuning condition, the coupling between two resonators is induced by a superconducting qubit. This coupling strength can be enhanced via a squeezing transformation.We study a generalized coupling system between a superconducting qubit and two nanomechanical resonators. When the eigenfrequency of the superconducting qubit is twice the frequency of the resonators, we show that one qubit is able to excite simultaneously two resonators. Moreover, tripartite and bipartite macroscopic entangled states are generated, respectively. We give conditions under which general tripartite and bipartite entangled nonorthogonal states become maximally entangled states. Under a large detuning condition, the coupling between two resonators is induced by a superconducting qubit. This coupling strength can be enhanced via a squeezing transformation.

Physical Review AOct 24, 201813 citations

Resonator-based superconducting qubit

Ivan N. Zhilyaev

Russian MicroelectronicsNov 1, 20050 citations

Circuit design implementing longitudinal coupling: A scalable scheme for superconducting qubits

Susanne Richer, David Peter Divincenzo

We present a circuit construction for a fixed-frequency superconducting qubit and show how it can be scaled up to a grid with strictly local interactions. The circuit QED realization we propose implements ${\ensuremath{\sigma}}_{z}$ type coupling between a superconducting qubit and any number of $LC$ resonators. The resulting longitudinal coupling is inherently different from the usual ${\ensuremath{\sigma}}_{x}$ type transverse coupling, which is the one that has been most commonly used for superconducting qubits. In a grid of fixed-frequency qubits and resonators with a particular pattern of always-on interactions, coupling is strictly confined to nearest and next-nearest neighbor resonators; there is never any direct qubit-qubit coupling. We note that just a single unique qubit frequency suffices for the scalability of this scheme. The same is true for the resonators, if the resonator-resonator coupling constants are varied instead. A controlled phase gate between two neighboring qubits can be realized with microwave drives on the qubits, without affecting the other qubits. This fact is a significant advantage for the scalability of this scheme.We present a circuit construction for a fixed-frequency superconducting qubit and show how it can be scaled up to a grid with strictly local interactions. The circuit QED realization we propose implements ${\ensuremath{\sigma}}_{z}$ type coupling between a superconducting qubit and any number of $LC$ resonators. The resulting longitudinal coupling is inherently different from the usual ${\ensuremath{\sigma}}_{x}$ type transverse coupling, which is the one that has been most commonly used for superconducting qubits. In a grid of fixed-frequency qubits and resonators with a particular pattern of always-on interactions, coupling is strictly confined to nearest and next-nearest neighbor resonators; there is never any direct qubit-qubit coupling. We note that just a single unique qubit frequency suffices for the scalability of this scheme. The same is true for the resonators, if the resonator-resonator coupling constants are varied instead. A controlled phase gate between two neighboring qubits can be realized with microwave drives on the qubits, without affecting the other qubits. This fact is a significant advantage for the scalability of this scheme.

arXiv:1511.06138Physical review. B./Physical review. BApr 4, 201685 citations

Control the qubit-qubit coupling with double superconducting resonators

Hui Wang, Rui Wang, Daichi Sugiyama +5 more

Jan 1, 20260 citations

LC

resonators. The resulting longitudinal coupling is inherently different from the usual ${\ensuremath{\sigma}}_{x}$ type transverse coupling, which is the one that has been most commonly used for superconducting qubits. In a grid of fixed-frequency qubits and resonators with a particular pattern of always-on interactions, coupling is strictly confined to nearest and next-nearest neighbor resonators; there is never any direct qubit-qubit coupling. We note that just a single unique qubit frequency suffices for the scalability of this scheme. The same is true for the resonators, if the resonator-resonator coupling constants are varied instead. A controlled phase gate between two neighboring qubits can be realized with microwave drives on the qubits, without affecting the other qubits. This fact is a significant advantage for the scalability of this scheme.