Google patents math method to check quantum computer accuracy
This filing describes a way to use standard computers to predict the results of quantum circuits. It converts quantum operations into a specific type of math puzzle called a graphical model to calculate the chance of getting a certain answer. This helps engineers test if real quantum hardware is working correctly.
In the filing’s own words
Methods, systems and apparatus for simulating quantum circuits including multiple quantum logic gates. In one aspect, a method includes the actions of representing the multiple quantum logic gates as functions of one or more classical Boolean variables that define a undirected graphical model with each classical Boolean variable representing a vertex in the model and each function of respective classical Boolean variables representing a clique between vertices corresponding to the respective classical Boolean variables; representing the probability of obtaining a particular output bit string from the quantum circuit as a first sum of products of the functions; and calculating the probability of obtaining the particular output bit string from the quantum circuit by directly evaluating the sum of products of the functions. The calculated partition function is used to (i) calibrate, (ii) validate, or (iii) benchmark quantum computing hardware implementing a quantum circuit.
What exactly they claim (claim 1)
1. A computer-implemented method for simulating a quantum circuit, the method comprising: representing multiple quantum logic gates included in the quantum circuit as functions of one or more classical Boolean variables, wherein the functions of one or more classical Boolean variables define an undirected graphical model with each classical Boolean variable representing a vertex in the undirected graphical model and each function of respective classical Boolean variables representing a clique between vertices corresponding to the respective classical Boolean variables; and calculating a probability of obtaining a particular output bit string from the quantum circuit, comprising: determining, based on an approximated treewidth of the defined undirected graphical model, an order of elimination for a variable elimination algorithm; and performing the variable elimination algorithm with the determined order of elimination to evaluate a sum of products of the functions.
Facts
- Company
- Google (Google LLC)
- Official title
- SIMULATION OF QUANTUM CIRCUITS
- Publication number
- US20260268190A1
- Application number
- 19205112
- Filed
- May 12, 2025
- Published
- Sep 10, 2026
- Inventors
- 2
- Claims
- 20
Classified under
G06N 10/20 Physics & computingG06F 30/3308 Physics & computingG06N 10/80 Physics & computingG06F 7/5443 Physics & computingMore from Google in AI & software
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Summaries are simplified from the filing’s own abstract and first claim. A patent filing is not a product announcement.
Patent data and drawings: U.S. Patent and Trademark Office (USPTO). Nebula is not affiliated with or endorsed by the USPTO.