Linear-Optical Quantum Operation Characterization From Photon Detection
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Solution Overview
Problem
Existing techniques for determining quantum operations performed by linear-optical quantum devices are inefficient or difficult to implement.
Innovation Solution
A method involving repeated implementation of quantum operations on a linear-optical quantum device, detection of photon presence or absence at photon detectors, calculation of marginal probabilities, and solving polynomial equations to estimate the quantum operation using a classical computer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing techniques are used to determine quantum operations performed by linear-optical quantum devices, then the quantum operation can be determined, but the process is difficult or inefficient to implement in practice
Solution Approach 1:
The patent replaces complex quantum measurement and characterization techniques with a classical computational approach. Instead of using complicated quantum tomography or interferometric methods, the system uses a classical computer to analyze detection data from photon detectors and solve polynomial equations to determine the quantum operation. This substitution of classical computation for quantum measurement techniques dramatically improves ease of implementation while maintaining efficiency.
2Reliability
If quantum operations are characterized to confirm intended operation, then verification is achieved, but the process becomes complex and inefficient
Solution Approach 1:
The patent creates a classical computational model that copies or replicates the quantum operation's mathematical description. By solving polynomial equations based on detection data, the system reconstructs the quantum operation as a set of parameters that can be verified against the intended operation. This copying approach allows verification without requiring complex quantum measurement apparatus, reducing device complexity while improving reliability through classical computational verification.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient characterization and verification of quantum operations performed by linear-optical quantum devices, allowing recreation of the operations on other quantum computers.
Implementation Method 1
a linear-optical quantum device, for example to allow the linear-optical quantum device to be verified
Implementation Method 2
detecting at each photon detector of the number of photon detectors the presence or lack of presence of at least one photon to form detection data
Data Source
Figure 1
Figure 2
Figure 3A~3F
AI summary
A method of determining a quantum operation being implemented by a linear-optical quantum device, the method comprising: repeatedly implementing the quantum operation on the linear-optical quantum device; and detecting at each photon detector of a number of photon detectors the presence or lack of presence of at least one photon to form detection data. The method further comprises determining, by a classical computer, a set of marginal probabilities using the detection data for each repetition of the quantum operation, forming, by the classical computer, a series of polynomial equations wherein the solutions to the series of polynomial equations are the set of marginal probabilities; and solving, by the classical computer, the series of polynomial equations to obtain an estimate of the quantum operation.