Comparison of Spontaneous Emission in Trapped Ion Multiqubit Gates at High Magnetic Fields

Abstract

Penning traps have been used for performing quantum simulations and sensing with hundreds of ions and provide a promising route toward scaling up trapped ion quantum platforms because of the ability to trap and control up to thousands of ions in 2D and 3D crystals. A leading source of decoherence in laser-based multiqubit operations on trapped ions is off-resonant spontaneous emission. While many trapped ion quantum computers or simulators utilize clock qubits, other systems rely on Zeeman qubits, which require a more complex calculation of this decoherence. We examine theoretically the impacts of spontaneous emission on quantum gates performed with trapped ions in a high magnetic field. We consider two types of gates -- light-shift and Molmer-Sorensen gates -- and compare the decoherence errors in each. We also compare different detunings, polarizations, and required intensities of the laser beams used to drive the gates. We show that both gates can have similar performance at their optimal operating conditions and examine the experimental feasibility of various operating points. By examining the magnetic field dependence of each gate, we demonstrate that when the $P$ state fine structure splitting is large compared to the Zeeman splittings, the theoretical performance of the Molmer-Sorensen gate is significantly better than that of the light-shift gate. Additionally, for the light-shift gate, we make an approximate comparison between the fidelities that can be achieved at high fields with the fidelities of state-of-the-art two-qubit trapped ion quantum gates. We show that, with regard to spontaneous emission, the achievable infidelity of our current configuration is about an order of magnitude larger than that of the best low-field gates, but we also discuss alternative configurations with potential error rates that are comparable with state-of-the-art trapped ion gates.

arXiv commentMain text: 19 pages, 13 figures, Appendix: 7 pages, 1 figure, updated to improve presentation

References in corpus (47)

• Trapped-Ion Quantum Computing: Progress and Challenges
• Quantum computation with ions in thermal motion
• Observation of a Many-Body Dynamical Phase Transition with a 53-Qubit Quantum Simulator
• Multi-particle entanglement of hot trapped ions
• Engineered 2D Ising interactions on a trapped-ion quantum simulator with hundreds of spins
• Observation of entanglement propagation in a quantum many-body system
• Programmable Quantum Simulations of Spin Systems with Trapped Ions
• Demonstration of a small programmable quantum computer with atomic qubits
• High-fidelity quantum logic gates using trapped-ion hyperfine qubits
• High-fidelity two-qubit quantum logic gates using trapped calcium-43 ions
• An ${}^{27}$Al${}^{+}$ quantum-logic clock with systematic uncertainty below $10^{-18}$
• Measuring out-of-time-order correlations and multiple quantum spectra in a trapped ion quantum magnet
• Quantum spin dynamics and entanglement generation with hundreds of trapped ions
• High-Fidelity Universal Gate Set for ${}^9$Be${}^{+}$ Ion Qubits
• 'Designer atoms' for quantum metrology
• Single ion-qubit exceeding one hour coherence time
• Entanglement and Tunable Spin-Spin Couplings Between Trapped Ions Using Multiple Transverse Modes
• Complete 3-Qubit Grover Search on a Programmable Quantum Computer
• Quantum-enhanced sensing of displacements and electric fields with large trapped-ion crystals
• Optimal quantum control of multi-mode couplings between trapped ion qubits for scalable entanglement
• Quantum information scrambling in a trapped-ion quantum simulator with tunable range interactions
• Errors in trapped-ion quantum gates due to spontaneous photon scattering
• High-Fidelity Bell-State Preparation with ${}^{40}$Ca${}^{+}$ Optical Qubits
• Cryogenic Trapped-Ion System for Large Scale Quantum Simulation
• Spin-dependent forces on trapped ions for phase-stable quantum gates and motional Schrodinger-cat states
• Observation of Domain Wall Confinement and Dynamics in a Quantum Simulator
• Quantum Simulation of Spin Models on an Arbitrary Lattice with Trapped Ions
• Observing emergent hydrodynamics in a long-range quantum magnet
• Coherent Error Suppression in Multi-Qubit Entangling Gates
• Decoherence due to elastic Rayleigh scattering
• Trapped Ion Quantum Information Processing with Squeezed Phonons
• Two-qubit entangling gates within arbitrarily long chains of trapped ions
• Non-equilibrium dynamics of Ising models with decoherence: an exact solution
• 2D ion crystals in radiofrequency traps for quantum simulation
• Sharp phase transitions in a small frustrated network of trapped ion spins
• Radial two-dimensional ion crystals in a linear Paul trap
• Controlling long ion strings for quantum simulation and precision measurements
• Laser-free trapped-ion entangling gates with simultaneous insensitivity to qubit and motional decoherence
• Phase-coherent sensing of the center-of-mass motion of trapped-ion crystals
• Photon scattering errors during stimulated Raman transitions in trapped-ion qubits
• A Wavelength-Insensitive, Multispecies Entangling Gate for Group-2 Atomic Ions
• Site-resolved imaging of beryllium ion crystals in a high-optical-access Penning trap with inbore optomechanics
• High Fidelity Entangling Gates in a 3D Ion Crystal under Micromotion
• A stroboscopic approach to trapped-ion quantum information processing with squeezed phonons
• Doppler Cooled Ions in a Compact, Reconfigurable Penning Trap
• Transport-enabled entangling gate for trapped ions
• Scalable quantum logic spectroscopy

Cited by in corpus (4)

• Errors in stimulated-Raman-induced logic gates in ${}^{133}$Ba${}^{+}$
• Bilayer crystals of trapped ions for quantum information processing
• In-situ-tunable spin-spin interactions in a Penning trap with in-bore optomechanics
• Parametric Amplification of Spin-Motion Coupling in Three-Dimensional Trapped-Ion Crystals