Technical manuscripts | Research | Q-CTRL Documentation

Experimental deep reinforcement learning for error-robust gateset design on a superconducting quantum computer

Quantum computers promise tremendous impact across applications - and have shown great strides in hardware engineering - but remain notoriously error prone.

Error-robust quantum logic optimization using a cloud quantum computer interface

We describe an experimental effort designing and deploying error-robust single-qubit operations using a cloud-based quantum computer and analog-layer programming access.

Quantum oscillator noise spectroscopy via displaced Schrödinger cat states

Joint oscillator modes fundamentally enable interactions between trapped ion qubits.

Numeric optimization for configurable, parallel, error-robust entangling gates in large ion registers

We study a class of entangling gates for trapped atomic ions and demonstrate the use of numeric optimization techniques to create a wide range of fast, error-robust gate constructions.

Software tools for quantum control: Improving quantum computer performance through noise and error suppression

Manipulating quantum computing hardware in the presence of imperfect devices and control systems is a central challenge in realizing useful quantum computers.

Convergence analysis for autonomous adaptive learning applied to quantum architectures

We present a formal analysis and convergence proofs for an autonomous adaptive learning algorithm useful for the tuneup and stabilization of quantum computing architectures.

Optimally band-limited controls for quantum multi-axis spectral estimation

The fragility of quantum systems makes them ideally suited for sensing applications at the nanoscale.

Dynamically corrected gates suppress spatio-temporal error correlations as measured by randomized benchmarking

Quantum error correction provides a path to large-scale quantum computers, but is built on challenging assumptions about the characteristics of the underlying errors.

Autonomous adaptive noise characterization in quantum computers

New quantum computing architectures consider integrating qubits as sensors to provide actionable information useful for decoherence mitigation on neighboring data qubits, but little work has addressed how such schemes may be efficiently implemented in order to maximize information utilization.

Qiskit Backend Specifications for OpenQASM and OpenPulse Experiments

As interest in quantum computing grows, there is a pressing need for standardized API's so that algorithm designers, circuit designers, and physicists can be provided a common reference frame for designing, executing, and optimizing experiments.

Phase-modulated entangling gates robust to static and time-varying errors

Entangling operations are among the most important primitive gates employed in quantum computing and it is crucial to ensure high-fidelity implementations as systems are scaled up.

Optimally band-limited spectroscopy of control noise using a qubit sensor

Classical control noise is ubiquitous in qubit devices, making its accurate spectral characterization essential for designing optimized error suppression strategies at the physical level.

Machine learning for predictive estimation of qubit dynamics subject to dephasing

Decoherence remains a major challenge in quantum computing hardware and a variety of physical-layer controls provide opportunities to mitigate the impact of this phenomenon through feedback and feedforward control.

Experimental quantum verification in the presence of temporally correlated noise

Growth in the complexity and capabilities of quantum information hardware mandates access to practical techniques for performance verification that function under realistic laboratory conditions.

Application of optimal band-limited control protocols to quantum noise sensing

Industrial, metrological, and medical applications provide a strong technological pull for advanced nanoscale sensors exploiting the unique sensitivity of quantum coherent systems to their environments.

A functional basis for efficient physical-layer classical control in quantum processors

The rapid progress seen in the development of quantum coherent devices for information processing has motivated serious consideration of quantum computer architecture and organization.

Prediction and real-time compensation of qubit decoherence via machine-learning

The wide-ranging adoption of quantum technologies requires practical, high-performance advances in our ability to maintain quantum coherence while facing the challenge of state collapse under measurement.

The role of master clock stability in scalable quantum information processing

Experimentalists seeking to improve the coherent lifetimes of quantum bits have generally focused on mitigating decoherence mechanisms through, for example, improvements to qubit designs and materials, and system isolation from environmental perturbations.

The effect of noise correlations on randomized benchmarking

Among the most popular and well studied quantum characterization, verification and validation techniques is randomized benchmarking (RB), an important statistical tool used to characterize the performance of physical logic operations useful in quantum information processing.

Walsh-synthesized noise-filtering quantum logic

We study a novel class of open-loop control protocols constructed to perform arbitrary nontrivial single-qubit logic operations robust against time-dependent non-Markovian noise.

Phase-modulated decoupling and error suppression in qubit-oscillator systems

We present a scheme designed to suppress the dominant source of infidelity in entangling gates between quantum systems coupled through intermediate bosonic oscillator modes.

Analytically exploiting noise correlations inside the feedback loop to improve locked-oscillator performance

We introduce concepts from optimal estimation to the stabilization of precision frequency standards limited by noisy local oscillators.

Experimental noise filtering by quantum control

Instabilities due to extrinsic interference are routinely faced in systems engineering, and a common solution is to rely on a broad class of filtering techniques in order to afford stability to intrinsically unstable systems.

Experimental bath engineering for quantitative studies of quantum control

We develop and demonstrate a technique to engineer universal unitary baths in quantum systems.

Robustness of composite pulses to time-dependent control noise

e study the performance of composite pulses in the presence of time-varying control noise on a single qubit.

Programmable quantum simulation by dynamic Hamiltonian engineering

Quantum simulation is a promising near term application for mesoscale quantum information processors, with the potential to solve computationally intractable problems at the scale of just a few dozen interacting quantum systems.

Arbitrary quantum control of qubits in the presence of universal noise

In this manuscript we address the problem of deriving \emph{analytic} expressions for calculating universal decoherence-induced errors in qubits undergoing arbitrary, unitary, time-dependent quantum-control protocols.

Long-time Low-latency Quantum Memory by Dynamical Decoupling

Quantum memory is a central component for quantum information processing devices, and will be required to provide high-fidelity storage of arbitrary states, long storage times and small access latencies.

High-order noise filtering in nontrivial quantum logic gates

Treating the effects of a time-dependent classical dephasing environment during quantum logic operations poses a theoretical challenge, as the application of non-commuting control operations gives rise to both dephasing and depolarization errors that must be accounted for in order to understand total average error rates.

Reducing sequencing complexity in dynamical quantum error suppression by Walsh modulation

We study dynamical error suppression from the perspective of reducing sequencing complexity, in order to facilitate efficient semi-autonomous quantum-coherent systems.

Phenomenological Study of Decoherence in Solid-State Spin Qubits due to Nuclear Spin Diffusion

We present a study of the prospects for coherence preservation in solid-state spin qubits using dynamical decoupling protocols.

Dynamical decoupling sequence construction as a filter-design problem

Over the past decade we have seen an explosion of demonstrations of quantum coherence in atomic, optical, and condensed matter systems.

High-fidelity quantum control using ion crystals in a Penning trap

We discuss the use of two-dimensional 9Be+ ion crystals for experimental tests of quantum control techniques.

Optimized Noise Filtration through Dynamical Decoupling

One approach to maintaining phase coherence of qubits through dynamical decoupling consists of applying a sequence of Hahn spin-echo pulses.

Experimental Uhrig Dynamical Decoupling using Trapped Ions

We present a detailed experimental study of the Uhrig Dynamical Decoupling (UDD) sequence in a variety of noise environments.

Optimized Dynamical Decoupling in a Model Quantum Memory

We present experimental measurements on a model quantum system that demonstrate our ability to dramatically suppress qubit error rates by the application of optimized dynamical decoupling pulse sequences in a variety of experimentally relevant noise environments.