Semiconductor qubits in practice

Abstract

In the past decade, semiconducting qubits have made great strides in overcoming decoherence, improving the prospects for scalability and have become one of the leading contenders for the development of large-scale quantum circuits. In this Review, we describe the current state of the art in semiconductor charge and spin qubits based on gate-controlled semiconductor quantum dots, shallow dopants and colour centres in wide-bandgap materials. We frame the relative strengths of the different semiconductor qubit implementations in the context of applications such as quantum simulation, computing, sensing and networks. By highlighting the status and future perspectives of the basic types of semiconductor qubits, this Review aims to serve as a technical introduction for non-specialists and a forward-looking reference for scientists intending to work in this field. Semiconductor qubits are expected to have diverse future quantum applications. This Review discusses semiconductor qubit implementations from the perspective of an ecosystem of applications, such as quantum simulation, sensing, computation and communication. Semiconductor qubits span an entire ecosystem and are extremely versatile in terms of quantum applications, particularly viewed through the lenses of quantum simulation, sensing, computation and communication. Controlling the charge degree of freedom in gated quantum dots is important for sensing of quantum objects, readout and light–matter coupling. Gate-controlled spin qubits have demonstrated long coherence times, fast two-qubit gates and fault-tolerant operation, with promising prospects for quantum computation. Shallow dopants have shown some of the longest coherence times in the solid state and high sensitivity to magnetic fields, relevant for quantum memories and sensing. Optically active defects have shown great promise as in situ sensors, and their natural ability to serve as spin–photon interfaces makes them suitable for long-distance quantum communication. Looking beyond a fault-tolerant quantum computer, semiconductor qubits will find diverse applications such as light–matter networks, scanning sensors, quantum memories, global cryptographic networks and small-scale designer simulation arrays. Semiconductor qubits span an entire ecosystem and are extremely versatile in terms of quantum applications, particularly viewed through the lenses of quantum simulation, sensing, computation and communication. Controlling the charge degree of freedom in gated quantum dots is important for sensing of quantum objects, readout and light–matter coupling. Gate-controlled spin qubits have demonstrated long coherence times, fast two-qubit gates and fault-tolerant operation, with promising prospects for quantum computation. Shallow dopants have shown some of the longest coherence times in the solid state and high sensitivity to magnetic fields, relevant for quantum memories and sensing. Optically active defects have shown great promise as in situ sensors, and their natural ability to serve as spin–photon interfaces makes them suitable for long-distance quantum communication. Looking beyond a fault-tolerant quantum computer, semiconductor qubits will find diverse applications such as light–matter networks, scanning sensors, quantum memories, global cryptographic networks and small-scale designer simulation arrays.