Semiconductor-inspired design principles for superconducting quantum computing

Abstract

Superconducting circuits offer tremendous design flexibility in the quantum regime culminating most recently in the demonstration of few qubit systems supposedly approaching the threshold for fault-tolerant quantum information processing. Competition in the solid-state comes from semiconductor qubits, where nature has bestowed some very useful properties which can be utilized for spin qubit-based quantum computing. Here we begin to explore how selective design principles deduced from spin-based systems could be used to advance superconducting qubit science. We take an initial step along this path proposing an encoded qubit approach realizable with state-of-the-art tunable Josephson junction qubits. Our results show that this design philosophy holds promise, enables microwave-free control, and offers a pathway to future qubit designs with new capabilities such as with higher fidelity or, perhaps, operation at higher temperature. The approach is also especially suited to qubits on the basis of variable super-semi junctions.

Entangling distant resonant exchange qubits via circuit quantum electrodynamics

“…Thus, driving qubit a such that its Rabi frequency is resonant with the difference between the qubit transition frequencies leads to an effective two-qubit interaction in the doubly rotating frame. Note that this interaction has the same form as (26). The unitary evolution generated by H drf dd is therefore of the same form as Eq.…”

“…The particular form of the exchange-only qubit known as the resonant exchange (RX) qubit enables high-frequency operation via resonant microwave driving of the exchange at a "sweet spot," where a large exchange energy gap suppresses the sensitivity of the qubit to lowfrequency charge noise. 17,18,[24][25][26] Thus, the RX qubit represents a semiconductor qubit similar to the transmon superconducting qubit 27,28 that additionally possesses the protection intrinsic to spin qubits. 3,6 A key element of a scalable quantum information processor based on multielectron spin qubits is the implementation of long-range entangling gates.…”

Controlled crack propagation for atomic precision handling of wafer-scale two-dimensional materials

“…ecause of their in-plane stability and weak out-of-plane interaction, two-dimensional (2D) materials can be stacked together to form a multitude of device types with a broad spectrum of functionalities (1)(2)(3)(4)(5)(6). Construction of 2D material-based heterostructures is often described as stacking Lego blocks (4).…”

Slow Electron–Phonon Cooling in Superconducting Diamond Films

“…The temperature of the superconducting transition increases with the carrier concentration, and can be varied between 1 K and 10 K by controlling the dopant level [9], [10]. The discovery of superconductivity in boron-doped diamond has opened the possibility to combine its outstanding mechanical and optical properties with superconductivity, which makes it a promising material for fully integrated hybrid systems [11], [12]. Our previous study of energy relaxation in single-crystalline borondoped diamond films epitaxially grown on a diamond shows a remarkably slow energy-relaxation at low temperatures [13].…”