Algorithms & Applications
11.07.23
Quantum relax-and-round algorithm for combinatorial optimization
We introduce a relax-and-round approach embedding the quantum approximate optimization algorithm (QAOA) with p≥1 layers.
Learn MoreResearch Publications Archive
The latest in Quantum Thinking
Entanglement across separate silicon dies in a modular superconducting qubit device
We demonstrate a modular solid state architecture with deterministic inter-module coupling between four physically separate, interchangeable superconducting qubit integrated circuits.
Learn More
Algorithms & Applications
30.03.23
Development and demonstration of an efficient readout error mitigation technique for use in NISQ algorithms
We consider the approximate state estimation of readout-mitigated expectation values, and how to best implement that procedure on the Rigetti quantum computing hardware. We discuss the theoretical aspects involved, providing an explicit computation of the effect of readout error on the estimated expectation values and how to mitigate that effect.
Learn More
Systems R&D
13.03.23
Navigating the noise-depth tradeoff in adiabatic quantum circuits
What is the optimal circuit depth that provides the best solution? Here, we address this question by investigating an adiabatic circuit that interpolates between the paramagnetic and ferromagnetic ground states of the one-dimensional quantum Ising model.
Learn More
Systems R&D
07.03.23
Direct pulse-level compilation of arbitrary quantum logic gates on superconducting qutrits
In this work, we demonstrate that any arbitrary qutrit gate can be realized with high fidelity. We generated and tested pulses for a large set of randomly selected arbitrary unitaries on two separate qutrit compatible processors, LLNL Quantum Device and Integration Testbed (QuDIT) standard QPU and Rigetti Aspen-11, achieving an average fidelity around 99 %.
Learn More
Systems R&D
10.02.23
Simulating the interplay of particle conservation and long-range coherence
We introduce two complementary probes of global and relative phase coherence, study how they are affected by measurements of the particle number, and implement them on a superconducting quantum computer by Rigetti.
Learn More
Systems R&D
19.01.23
Preparing quantum many-body scar states on quantum computers
Our recent work has proposed both unitary and non-unitary state preparation protocols for quantum many-body scar states and their superposition states. Their successful implementation on Aspen M-2 shows a PoC and will serve as a solid starting point for the future study of quantum many-body dynamics.
Algorithms & Applications
30.12.22
Calibrating the classical hardness of the quantum approximate optimization algorithm
Trading fidelity for scale enables approximate classical simulators such as matrix product states (MPS) to run quantum circuits beyond exact methods. A control parameter, the so-called bond dimension χ for MPS, governs the allocated computational resources and the output fidelity.
Learn More
Systems R&D
14.11.22
Hardware optimized parity check gates for superconducting surface codes
Our central consideration, Hardware Optimized Parity (HOP) gates, achieves stabilizer-type measurements through simultaneous multi-qubit conditional phase accumulation. Despite the multi-body effects that underpin this approach, our estimates of logical faults suggest that this design can be at least as robust to realistic noise as conventional designs.
Learn More
Algorithms & Applications
22.08.22
Entanglement perspective on the quantum approximate optimization algorithm
Here, we consider the QAOA algorithm for solving the paradigmatic Max-Cut problem on different types of graphs. We study the entanglement growth and spread resulting from randomized and optimized QAOA circuits and find that there is a volume-law entanglement barrier between the initial and final states.
Learn More
Systems R&D
18.05.22
Dynamical sweet spot engineering via two-tone flux modulation of superconducting qubits
We experimentally demonstrate that two-tone flux modulation can be used to create a continuum of dynamical sweet spots.
Learn More
Algorithms & Applications
30.11.21
Synthetic weather radar using hybrid quantum-classical machine learning
We demonstrate methods to augment conventional convolutional neural networks with quantum-assisted models for generative tasks in global synthetic weather radar.
Learn More
Systems R&D
04.10.21
Full control of superconducting qubits with combined on-chip microwave and flux lines
We present a method to integrate a microwave line and a flux line into a single "XYZ line."
Learn MoreDisplaying 25–36 of 76 results