Abstract
In this letter, it is proposed that cryogenic quantum bits can operate based on the nonlinearity due to the quantum capacitance of two-dimensional Dirac materials, and in particular graphene. The anharmonicity of a typical superconducting quantum bit is calculated, and the sensitivity of quantum bit frequency and anharmonicity with respect to temperature are found. Reasonable estimates reveal that a careful fabrication process can reveal expected properties, putting the context of quantum computing hardware into new perspectives.
Highlights
We discuss a new type of qubit with integrability, based on a nonlinear quantum capacitor (QC) made of two-dimensional materials [1], graphene (Gr), and boron nitride (BN) and their heterostructures [2,3]
The nonlinear inductance is replaced by the nonlinear capacitance coming from two Gr monolayers separated by a multilayer BN, which acts as a potential barrier and forms a parallel plate capacitance [1]
The graphene/boron nitride/graphene sandwich structure seems to be promising for quantum bit applications, where the nonlinearity of quantum capacitance replaces the nonlinearity of Josephson junctions (JJs)
Summary
We discuss a new type of qubit with integrability, based on a nonlinear quantum capacitor (QC) made of two-dimensional materials [1], graphene (Gr), and boron nitride (BN) and their heterostructures [2,3]. Recent discoveries on the existence of the p-wave-induced phase of superconductivity in Gr [15] as well as the unconventional superconducting phase of the twisted bilayer Gr at the magic angle of 19.19mRad [16] raises hopes for the practicality of such a design The latter offers a large decrease in Fermi velocity at the vicinity of Dirac cone, which helps in a significant reduction in qubit size as well as the relaxation of stringing limits imposed by the fabrication technology. It is the purpose of this letter to establish the feasibility of CUBIT, which we use to refer to the nonlinear Capacitive qUantum BIT. Another potentially useful application of nonlinear quantum capacitance could be in the cryogenic quantum-limited parametric amplifiers
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