Coupling superconducting qubits via a cavity bus

By J. Majer, Jerry M. Chow, Jay M. Gambetta, Jens Koch, Blake R. Johnson, J. Schreier, Luigi Frunzio, David I. Schuster, Andrew A. Houck, A. Wallraff and 4 more. Nature, 2007

1,192 citations recorded by the source corpus.

Superconducting circuits are promising candidates for constructing quantum bits (qubits) in a quantum computer; single-qubit operations are now routine, and several examples of two-qubit interactions and gates have been demonstrated. These experiments show that two nearby qubits can be readily coupled with local interactions. Performing gate operations between an arbitrary pair of distant qubits is highly desirable for any quantum computer architecture, but has not yet been demonstrated. An efficient way to achieve this goal is to couple the qubits to a ‘quantum bus’, which distributes quantum information among the qubits. Here we show the implementation of such a quantum bus, using microwave photons confined in a transmission line cavity, to couple two superconducting qubits on opposite sides of a chip. The interaction is mediated by the exchange of virtual rather than real photons, avoiding cavity-induced loss. Using fast control of the qubits to switch the coupling effectively on and off, we demonstrate coherent transfer of quantum states between the qubits. The cavity is also used to perform multiplexed control and measurement of the qubit states. This approach can be expanded to more than two qubits, and is an attractive architecture for quantum information processing on a chip.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/fb95f204372d7f82bb16f361b17b43286e6067be

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Artificial Intelligence

In Atomic and Molecular Physics, and Optics

Citations in the corpus

Analog information processing at the quantum limit with a Josephson ring modulator (2008, background): “However, recent progress in quantum information processing using microwave interrogation of solid states qubits[13, 14, 15, 16] gave rise to a growing need for low-noise amplifiers which are sensitive enough to measure the extremely weak signals involved in these new devices and renewed the interest”
Quantum information processing with superconducting circuits: a review (2016, methodology): “(i) Microwave qubit control, strong qubitresonator coupling and dispersive readout [23]; (ii) Coupling of CPB qubits and swapping excitations, in practice implementing a universal √ iSWAP gate [24].”
Quantum many‐body phenomena in coupled cavity arrays (2008, methodology): “Very large cooperativity factors have been achieved in this set-up [62,112] and the nonlinearity of the Jaynes-Cummings model has been measured [113].”
Circuit quantum electrodynamics (2020, background): “An entangling gate can thus be performed in the same way as with direct capacitive coupling, either by tuning the qubits in and out of resonance with each other (Majer et al., 2007) or by making the couplings gi tunable (Gambetta et al., 2011a; Srinivasan et al., 2011).”
Scalable designs for quasiparticle-poisoning-protected topological quantum computation with Majorana zero modes (2016, methodology): “The resonator frequency will have a parity-dependent frequency shift ω which can be detected using the reflectometry technique [58].”