Charge-insensitive qubit design derived from the Cooper pair box

By Jens Koch, Terri M. Yu, Jay M. Gambetta, Andrew A. Houck, David I. Schuster, J. Majer, Alexandre Blais, Michel H. Devoret, Steven M. Girvin, Robert J. Schoelkopf. 2007

3,004 citations recorded by the source corpus.

Short dephasing times pose one of the main challenges in realizing a quantum computer. Different approaches have been devised to cure this problem for superconducting qubits, a prime example being the operation of such devices at optimal working points, so-called 'sweet spots.' This latter approach led to significant improvement of T{sub 2} times in Cooper pair box qubits [D. Vion et al., Science 296, 886 (2002)]. Here, we introduce a new type of superconducting qubit called the 'transmon'. Unlike the charge qubit, the transmon is designed to operate in a regime of significantly increased ratio of Josephson energy and charging energy E{sub J}/E{sub C}. The transmon benefits from the fact that its charge dispersion decreases exponentially with E{sub J}/E{sub C}, while its loss in anharmonicity is described by a weak power law. As a result, we predict a drastic reduction in sensitivity to charge noise relative to the Cooper pair box and an increase in the qubit-photon coupling, while maintaining sufficient anharmonicity for selective qubit control. Our detailed analysis of the full system shows that this gain is not compromised by increased noise in other known channels.

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

View Paper: https://www.semanticscholar.org/paper/92ea42c577990e26fbb498ae05c8abb22f23f2e2

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Citations in the corpus

The 2019 surface acoustic waves roadmap (2019, background): “In 2014, it was shown [31] that a superconducting qubit could be coupled to SAWs by forming the capacitance of a transmon qubit [32] into an interdigitated transducer (IDT) (see figure 2).”
Open Quantum Assembly Language (2017, background): “The state of which is manipulated by applying a series of shaped microwave control pulses [52].”
High-Fidelity, Frequency-Flexible Two-Qubit Fluxonium Gates with a Transmon Coupler (2023, background): “While there exists a large selection of superconducting qubits, almost all advancements toward processors at scale have been carried forward with the transmon qubit [4], a simple circuit consisting of a Josephson junction in parallel with a shunt capacitance.”
Giant acoustic atom: A single quantum system with a deterministic time delay (2016, background): “The single two-level quantum system is realized by a transmon qubit [30] with strong nonlinearity, which serves as an artificial atom.”
Atomic physics and quantum optics using superconducting circuits (2011, methodology): “Also, this large capacitance shunted to the Josephson junction can be used to reduce the charge noise in the Cooper-pair box [12], so as to implement the circuit in the phase regime.”
Materials challenges and opportunities for quantum computing hardware (2021, background): “Instead, the issue has so far been addressed through qubit design by adding a large shunting capacitor ( 38 ) or an inductor ( 40 ) to suppress the sensitivity to charge noise.”
Scalable Quantum Simulation of Molecular Energies (2015, methodology): “Both algorithms are implemented with a superconducting quantum system based on the Xmon [48], a variant of the planar transmon qubit [49], in a dilution refrigerator with a base temperature of 20 mK.”
Evidence for the utility of quantum computing before fault tolerance (2023, methodology): “For the experimental implementation, we primarily used the IBM Eagle processor ibm_kyiv, composed of 127 fixed-frequency transmon qubits 15 with heavy-hex connectivity and median T 1 and T 2 times of 288 μs and 127 μs, respectively.”
Rapid High-Fidelity Single-Shot Dispersive Readout of Superconducting Qubits (2017, methodology): “Charge dispersion scales exponentially with the ratio of the Josephson energy to the charging energy, EJ/EC [34] and therefore with the qubit frequency and anharmonicity.”
Quantum information processing and quantum optics with circuit quantum electrodynamics (2020, background): “There are many types of superconducting qubits, and here we focus on the transmon, which is the simplest and most widely used 18 .”
Observation of the Photon-Blockade Breakdown Phase Transition (2016, background): “Similar to a harmonic oscillator, the coupling strength of the second excited level can be approximated [40] as g2 ≃ ffiffiffi 2 p g1.”
Observation of a Dissipation-Induced Classical to Quantum Transition (2013, background): “Dephasing for our choice of qubits (transmons) can be made much weaker than the above two channels [38, 39], and hence is ignored in our theoretical description.”