Optimal calibration of gates in a quantum computing system
Inventors
MAKSYMOV, Andrii • NIROULA, Pradeep • NAM, Yunseong
Assignees
University of Maryland Baltimore • University of Maryland College Park • IonQ Inc
Publication Number
US-12229603-B2
Publication Date
2025-02-18
Expiration Date
2041-11-19
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Abstract
A method of performing a quantum computation process includes mapping logical qubits to physical qubits of a quantum processor so that quantum circuits are executable using the physical qubits of the quantum processor and a total infidelity of the plurality of quantum circuits is minimized, wherein each of the physical qubits comprise a trapped ion, and each of the plurality of quantum circuits comprises single-qubit gates and two-qubit gates within the plurality of the logical qubits, calibrating two-qubit gates within a first plurality of pairs of physical qubits, such that infidelity of the two-qubit gates within the first plurality of pairs of physical qubit is lowered, executing the plurality of quantum circuits on the quantum processor, by applying laser pulses that each cause a single-qubit gate operation and a two-qubit gate operation in each of the plurality of quantum circuits on the plurality of physical qubits, measuring population of qubit states of the physical qubits in the quantum processor, and outputting the measured population of qubit states of the physical qubits.
Core Innovation
The invention provides a method and system for performing a quantum computation process by mapping logical qubits to physical qubits in a quantum processor composed of trapped ions, so as to execute quantum circuits while minimizing total infidelity. The process includes calibrating two-qubit gates within selected pairs of physical qubits to reduce gate infidelity, executing the circuits by applying laser pulses for gate operations, measuring the resulting qubit states, and outputting the results via a classical computer.
A core aspect of the innovation is the optimization of calibration resources by selecting a subset of two-qubit gates for calibration that maximizes computational fidelity within a fixed calibration budget. This is achieved by representing quantum circuits and processor connectivity as graphs and introducing techniques such as most compact cumulative supergraph (MCCS) algorithms and genetic algorithms to identify the most beneficial pairs of qubits for calibration. The approach minimizes calibration effort while maintaining execution fidelity.
The problem addressed is that calibration in trapped-ion quantum computing systems is expensive and time-consuming, scaling quadratically with the number of qubits due to the need for repeated measurements over many control parameters. Existing methods result in significant resource requirements and degraded calibration quality as system size increases, thereby necessitating a means to minimize calibration resource use while achieving reliable computational results.
Claims Coverage
The independent claims cover three main inventive features as disclosed in the patent.
Quantum computation process with optimized mapping and calibration of two-qubit gates
A method for performing a quantum computation process comprising: - Mapping logical qubits to physical qubits (trapped ions) such that quantum circuits can be executed using the physical qubits. - Calibrating (adjusting amplitude and frequency of laser pulses) two-qubit gates among specific pairs of physical qubits to correct errors in those gates. - Executing quantum circuits by applying laser pulses that result in both single-qubit and two-qubit gate operations on the physical qubits. - Measuring the population of qubit states after execution and outputting these measured results for display, storage, or transfer.
Quantum computing system with mapped calibration and execution functionality
A quantum computing system comprising: - A quantum processor having physical qubits constituted by trapped ions. - A classical computer configured to map logical qubits to physical qubits so that quantum circuits (including single-qubit and two-qubit gates) are executable. - A system controller configured to adjust laser pulse amplitude and frequency for two-qubit gates on selected pairs to correct errors; execute circuits by applying appropriate laser pulses; and measure qubit states after execution. - The classical computer further outputs the measured populations for display, storage, or transfer.
Non-volatile memory-based quantum computing system for optimized quantum computation
A quantum computing system comprising non-volatile memory storing instructions which, when executed by one or more processors, cause the system to: - Map logical qubits to physical qubits (trapped ions) for executable quantum circuits. - Calibrate two-qubit gates by adjusting amplitude and frequency of laser pulses for selected pairs of physical qubits. - Execute circuits using single-qubit and two-qubit laser pulse operations, measure the resulting qubit populations, and output these results for display, storage, or transfer.
These inventive features collectively define a method and system for improving quantum computation fidelity in trapped-ion processors by optimizing the calibration of two-qubit gates through mapping, calibration, execution, and result output processes.
Stated Advantages
Significantly reduces the calibration resource required for two-qubit gates in quantum computing systems while maintaining high computational fidelity.
Enables scalable and reliable quantum computation by optimizing which two-qubit gates are calibrated within a fixed calibration budget.
Provides increased average algorithm fidelity compared to primitive or naive calibration approaches, as shown in simulation results.
Substantially decreases the time and computational resources needed to reach target fidelities, especially as system size increases.
Enables more efficient circuit compiling and execution, potentially allowing smaller quantum computers to contribute to calibration of larger systems.
Documented Applications
Quantum circuit compiling and the execution of quantum algorithms in ion-trap quantum computing systems.
Acceleration of various numerical optimization problems using more reliable and scalable quantum computation.
Optimization of calibration routines for both current and future larger-sized quantum computers.
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