Realization and Calibration of Continuously Parameterized Two-Qubit Gates on a Trapped-Ion Quantum Processor

Abstract

Continuously parameterized two-qubit gates are a key feature of state-of-the-art trapped-ion quantum processors as they have favorable error scalings and show distinct improvements in circuit performance over more restricted maximally entangling gatesets. In this work, we provide a comprehensive and pedagogical discussion on how to practically implement these continuously parameterized Mølmer-Sørensen gates on the Quantum Scientific Computing Open User Testbed (QSCOUT), a low-level trapped-ion processor. To generate the arbitrary entangling angles, $\theta$, we simply scale the amplitude of light used to generate the entanglement. However, doing so requires careful consideration of amplifier saturation as well as the variable light shifts that result. As such, we describe a method to calibrate and cancel the dominant fourth-order effects, followed by a dynamic virtual phase advance during the gate to cancel any residual light shifts, and find a linear scaling between $\theta$ and the residual light shift. Once, we have considered and calibrated these effects, we demonstrate performance improvement with decreasing $\theta$. Finally, we describe nuances of hardware control to transform the XX-type interaction of the arbitrary-angle Mølmer-Sørensen gate into a phase-agnostic and crosstalk-mitigating ZZ interaction.

17 pages, 16 figures

References in corpus (24)

• Quantum computation with ions in thermal motion
• Multi-particle entanglement of hot trapped ions
• High-fidelity two-qubit quantum logic gates using trapped calcium-43 ions
• High-fidelity quantum logic gates using trapped-ion hyperfine qubits
• Towards fault-tolerant quantum computing with trapped ions
• A Race Track Trapped-Ion Quantum Processor
• Parallel Entangling Operations on a Universal Ion Trap Quantum Computer
• Phase Control of Trapped Ion Quantum Gates
• Ultrafast Gates for Single Atomic Qubits
• Robust two-qubit gates in a linear ion crystal using a frequency-modulated driving force
• Entangling logical qubits with lattice surgery
• Deterministic entanglement of ions in thermal states of motion
• Multi-Species Trapped Ion Node for Quantum Networking
• Benchmarking a trapped-ion quantum computer with 30 qubits
• Resilient entanglement gates for trapped ions
• Re-examining the quantum volume test: Ideal distributions, compiler optimizations, confidence intervals, and scalable resource estimations
• Engineering Large Stark Shifts for Control of Individual Clock State Qubits
• Measurement-free fault-tolerant quantum error correction in near-term devices
• Engineering the Quantum Scientific Computing Open User Testbed (QSCOUT): Design details and user guide
• Batch Optimization of Frequency-Modulated Pulses for Robust Two-qubit Gates in Ion Chains
• Designing Filter Functions of Frequency-Modulated Pulses for High-Fidelity Two-Qubit Gates in Ion Chains
• Subspace benchmarking high-fidelity entangling operations with trapped ions
• First-Order Crosstalk Mitigation in Parallel Quantum Gates Driven With Multi-Photon Transitions
• A simplified Mølmer-Sørensen gate for the trapped ion quantum computer

Cited by in corpus (1)

• Crosstalk Insensitive Trapped-Ion Entanglement through Coupling Matrix Engineering