Demonstration of two-qubit algorithms with a superconducting quantum processor

By Leonardo DiCarlo, Jerry M. Chow, Jay M. Gambetta, Lev S. Bishop, Blake R. Johnson, David I. Schuster, J. Majer, Alexandre Blais, Luigi Frunzio, Steven M. Girvin and 1 more. Nature, 2009

1,104 citations recorded by the source corpus.

Quantum computers, which harness the superposition and entanglement of physical states, could outperform their classical counterparts in solving problems with technological impact—such as factoring large numbers and searching databases. A quantum processor executes algorithms by applying a programmable sequence of gates to an initialized register of qubits, which coherently evolves into a final state containing the result of the computation. Building a quantum processor is challenging because of the need to meet simultaneously requirements that are in conflict: state preparation, long coherence times, universal gate operations and qubit readout. Processors based on a few qubits have been demonstrated using nuclear magnetic resonance, cold ion trap and optical systems, but a solid-state realization has remained an outstanding challenge. Here we demonstrate a two-qubit superconducting processor and the implementation of the Grover search and Deutsch–Jozsa quantum algorithms. We use a two-qubit interaction, tunable in strength by two orders of magnitude on nanosecond timescales, which is mediated by a cavity bus in a circuit quantum electrodynamics architecture. This interaction allows the generation of highly entangled states with concurrence up to 94 per cent. Although this processor constitutes an important step in quantum computing with integrated circuits, continuing efforts to increase qubit coherence times, gate performance and register size will be required to fulfil the promise of a scalable technology.

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

View Paper: https://www.semanticscholar.org/paper/72b9ba83c7e90c21e5269e545dea7c6f10fd1bad

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Citations in the corpus

Simulating chemistry using quantum computers. (2010, methodology): “Examples of applications based on superconducting qubits include the tailor-made generation of harmonic oscillator states (55) and the implementation of the Deutsch-Jozsa and Grover quantum algorithms (36).”
Efficient Z gates for quantum computing (2016, background): “Refs [12, 20]), then these single-qubit Z terms commute through and can be compensated by a subsequent VZ-gate.”
Implementation of a Toffoli gate with superconducting circuits (2011, methodology): “shown significant progress recently: two-qubit algorithms [10] and two-qubit process tomography have been implemented [11], three-qubit entangled states have been prepared [12, 13], first steps towards quantum teleportation have been taken [14] and work on quantum computing ar-”
Colloquium: Strongly interacting photons in one-dimensional continuum (2016, background): “A number of physical systems are being actively investigated for implementing quantum nodes (De Greve et al., 2012; DiCarlo et al., 2009; Gao et al., 2012; Ritter et al., 2012; Sherson et al., 2006) with superconducting circuits in open environment being one of the promising candidates.”
Freely Scalable Quantum Technologies using Cells of 5-to-50 Qubits with Very Lossy and Noisy Photonic Links (2014, background): “In SQDs a well established means of interfacing qubits is to exploit microwave photons in cavities [9].”
Cryo-CMOS Circuits and Systems for Quantum Computing Applications (2018, background): “Two-qubit operations typically require current (for transmons [19]) or voltage pulses (for spin qubits [17]) with a bandwidth of tens of MHz.”