Controlling quantum computing system to determine quantity of object

Patent metadata

Field	Value
Publication number	US-2024428115-A1
Application number	US-202418742960-A
Country	US
Kind code	A1
Filing date	Jun 13, 2024
Priority date	Jun 14, 2023
Publication date	Dec 26, 2024
Grant date	—

Abstract

A system may receive a function ƒ(x) describing a value of an object, values of x, and probabilities p(x) for the values of x. The system may determine a quantum operator U + {right arrow over (ϕ)} that, when executed by a quantum computing system, encodes an approximation of the function ƒ(x) in an amplitude of a quantum state without calculating |ƒ(x) for any of the values of x. The system may instruct the quantum computing system to execute quantum operators (including U + {right arrow over (ϕ)} ) to generate a quantum state on a register of qubits, where one of the amplitudes of the generated quantum state includes probabilities p(x) for the values of x and output values of the approximation of the function ƒ(x) for the values of x. The system may determine the value of the object based on the generated quantum state.

First claim

What is claimed is:

1 . A method comprising:
receiving a function ƒ(x) describing a value of an object, values of x, and probabilities p(x) for the values of x; receiving a quantum operator P that, when executed by a first quantum computing system, creates a first quantum state characterized by a superposition of states encoding the x values, where the amplitude for a corresponding x value is the square root of the probability p(x) for that x value; determining a quantum operator U + {right arrow over (ϕ)} that, when executed by a second quantum computing system, encodes an approximation of the function ƒ(x) in an amplitude of a second quantum state without calculating |ƒ(x) for any of the values of x, the approximation being within an error threshold of the function ƒ(x); instructing a third quantum computing system to execute both of the quantum operators P and U + {right arrow over (ϕ)} to generate a third quantum state on a register of qubits, one of the amplitudes of the third quantum state including probabilities p(x) for the values of x and output values of the approximation of the function ƒ(x) for the values of x; and determining the value of the object based on the generated third quantum state.

2 . The method of claim 1 , wherein the method does not include calculating |ƒ(x) .

3 . The method of claim 1 , wherein the one of the amplitudes of the third quantum state is the square root of the weighted average of the approximation of the function ƒ(x) for the x values where the weights are the probabilities p(x) for the corresponding values of x.

4 . The method of claim 1 , wherein the first quantum state is given by Σ x √{square root over (p(x))}|x , where |x is a quantum state on an n-qubit register storing an n-bit binary representation of the corresponding value of x.

5 . The method of claim 1 , further comprising:
determining s, where s is based on the absolute values of the x values; and instructing the third quantum computing system to apply a quantum binary addition circuit that performs the operation: |x |0 →|x |x+s , where n and m are integers greater than zero, m>n, |x is a quantum state on an n-qubit register storing an n-bit binary representation of a value of x, and |x+s is a quantum state on an m-qubit register storing a representation of a value of x+s with m total digits and p digits to the left of the binary point.

6 . The method of claim 5 , wherein s is the absolute value of the smallest x value of the values of x.

7 . The method of claim 1 , wherein determining the quantum operator U + {right arrow over (ϕ)} , comprises generating an initial quantum operator given by U=C( ⊗H ⊗m ⊗ ), where C is a comparator quantum circuit defined by C:|a |b |0 →|a |b |a<b , is an identity matrix, and H is a Hadamard gate.

8 . The method of claim 7 , wherein determining the quantum operator U + {right arrow over (ϕ)} further comprises applying the initial quantum operator U to state |x+s |0 m+1 to generate the following quantum state:

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Assignees

• Goldman Sachs & Co Llc

Inventors

• Stamatopoulos Nikitas
• Zeng William Joesph

Classifications

• G06N10/00 Primary

  Quantum computing, i.e. information processing based on quantum-mechanical phenomena · CPC title

• G06N10/60 Primary

  Quantum algorithms, e.g. based on quantum optimisation, quantum Fourier or Hadamard transforms · CPC title

• G06N10/40 Primary

  Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control · CPC title

• B82Y10/00

  Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title

• G06N10/20 Primary

  Models of quantum computing, e.g. quantum circuits or universal quantum computers · CPC title