Bosonic Qubit Simulation via Gaussian Phase Space

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Solution Overview

Problem

Current methods for simulating bosonic qubits on classical computers face challenges due to the infinite-dimensionality of Hilbert space, leading to cumbersome simulations, high memory loads, and processing times, especially when dealing with high-energy cat and GKP states, which are essential for fault-tolerant quantum computing.

Innovation Solution

The method involves representing bosonic qubits as linear combinations of Gaussian functions in phase space, allowing for fast and accurate simulation of GKP, cat, and Fock states under Gaussian and non-Gaussian transformations and measurements, using a classical computer to update weight coefficients, means, and covariance matrices of Gaussian functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the Fock basis method is used to simulate bosonic qubits, then the simulation can be performed with existing tools, but the memory load and processing time increase significantly for high-energy states

Engineering Contradiction:
Improvesimulation accuracyVSAvoidmemory load
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the basis representation parameter from Fock basis to Gaussian function basis. This parameter change allows the same quantum states to be represented with fewer parameters, reducing memory requirements while maintaining simulation accuracy for high-energy bosonic qubit states.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the quantum state representation into a linear combination of Gaussian functions, each characterized by specific parameters (mean, covariance matrix, weight coefficient). This segmentation allows efficient storage and manipulation of high-energy states that would require excessive memory in the Fock basis.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the Fock basis method is used to simulate bosonic qubits, then the simulation framework is established, but the processing time becomes excessively long for high-energy cat and GKP states

Engineering Contradiction:
Improvesimulation accuracyVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the basis representation parameter from Fock basis to Gaussian function basis. This parameter change allows the same quantum states to be represented with fewer parameters, reducing memory requirements while maintaining simulation accuracy for high-energy bosonic qubit states.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the quantum state representation into a linear combination of Gaussian functions, each characterized by specific parameters (mean, covariance matrix, weight coefficient). This segmentation allows efficient storage and manipulation of high-energy states that would require excessive memory in the Fock basis.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If high photon-number cutoff is used to simulate high-quality cat and GKP states, then the simulation accuracy improves, but the memory load and processing time increase significantly

Engineering Contradiction:
Improvesimulation precisionVSAvoidmemory load
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent changes the basis representation parameter from Fock basis to Gaussian function basis. This parameter change allows the same quantum states to be represented with fewer parameters, reducing memory requirements while maintaining simulation accuracy for high-energy bosonic qubit states.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the quantum state representation into a linear combination of Gaussian functions, each characterized by specific parameters (mean, covariance matrix, weight coefficient). This segmentation allows efficient storage and manipulation of high-energy states that would require excessive memory in the Fock basis.

Inventive Principle:
Principle #1Segmentation

4Measurement precision

If high photon-number cutoff is used to simulate high-quality cat and GKP states, then the simulation precision improves, but the processing time increases significantly

Engineering Contradiction:
Improvesimulation precisionVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent changes the basis representation parameter from Fock basis to Gaussian function basis. This parameter change allows the same quantum states to be represented with fewer parameters, reducing memory requirements while maintaining simulation accuracy for high-energy bosonic qubit states.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the quantum state representation into a linear combination of Gaussian functions, each characterized by specific parameters (mean, covariance matrix, weight coefficient). This segmentation allows efficient storage and manipulation of high-energy states that would require excessive memory in the Fock basis.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS20230169382A1System and method of bosonic qubits simulation
Publication Date: 2023.06.01 XANADU QUANTUM TECHNOLOGIES HOLDINGS ULC
  • US20230169382A1 patent drawing
  • US20230169382A1 patent drawing
  • US20230169382A1 patent drawing

AI summary

A method for simulating a bosonic quantum bit (qubit) on a classical computer are described. The method determines a phase space representation of the qubit in the form of a linear combination of Gaussian functions, each of which is characterized by a mean, a covariance matrix, and a weight coefficient determined from user defined energy parameter and qubit class of the qubit. The qubit may be simulated on a classical computer by applying transformations of quantum logic gates and measurements to update the weight coefficient, mean, and covariance matrix of each of the Gaussian functions.