Controlled-Not Quantum Logic Gate in Two Strongly Coupled Semiconductor Charge Qubits

Abstract

A crucial requirement for scalable quantum-information processing is the realization of multiple-qubit quantum gates. Universal multiple-qubit gates can be implemented by a set of universal single qubit gates and any one kind of two-qubit gate, such as a controlled-NOT (CNOT) gate. Semiconductor quantum dot qubits are a leading approach for the physical implementation of quantum computation, due to their potential for large-scale integration. Two-qubit gate operations have been so far only demonstrated in individual electron spin-based quantum dot systems. Due to the relatively short de-coherence time, charge qubits in quantum dots are generally considered to be inferior for going beyond single qubit level. Here, we demonstrate the benchmarking CNOT gate in two capacitively coupled charge qubits, each consisting of an electron confined in a GaAs/AlGaAs double quantum dot. Owing to the strong inter-qubit coupling strength, gate operations with a clock speed up to 5GHz has been realized. A processing tomography shows encouragingly that the universal two-qubit gate operations have comparable fidelities to that of spin-based two-qubit gates. Our results suggest that semiconductor charge qubits have a considerable potential for scalable quantum computing and may stimulate the use of long-range Coulomb interaction for coherent quantum control in other devices.

References in corpus (18)

• Spins in few-electron quantum dots
• Silicon Quantum Electronics
• Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor
• A single-atom electron spin qubit in silicon
• Coherent manipulation of electronic states in a double quantum dot
• Quantum oscillations in two coupled charge qubits
• Coherent quantum state storage and transfer between two phase qubits via a resonant cavity
• Demonstration of conditional gate operation using superconducting charge qubits
• Demonstration of Entanglement of Electrostatically Coupled Singlet-Triplet Qubits
• High-fidelity readout and control of a nuclear spin qubit in silicon
• Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot
• Quantum Coherence in a One-Electron Semiconductor Charge Qubit
• Quantum control and process tomography of a semiconductor quantum dot hybrid qubit
• Quantum Process Tomography of a Universal Entangling Gate Implemented with Josephson Phase Qubits
• Two-qubit Gate of Combined Single Spin Rotation and Inter-dot Spin Exchange in a Double Quantum Dot
• Microwave-driven coherent operations of a semiconductor quantum dot charge qubit
• Fast coherent manipulation of three-electron states in a double quantum dot
• Conditional operation of a spin qubit