In-situ Gaussian Boson Sampling Characterization
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Solution Overview
Problem
Existing methods for characterizing Gaussian Boson Sampling (GBS) devices rely on classical light and intensity detectors, which introduce systematic errors due to differences between classical and quantum light sources, and require additional components, making them inefficient for determining the transformation matrix of linear optical interferometers.
Innovation Solution
The method involves using only the squeezed light and photon-number-resolving detectors from the GBS device itself, systematically turning on and off squeezed light sources and measuring photon statistics to determine the elements of the transformation matrices implemented by the linear optical interferometer, without introducing additional components, and utilizing correlation functions to estimate amplitudes and phases of the transformation matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If classical light and intensity detectors are used for characterizing GBS devices, then the characterization can be performed with conventional equipment, but systematic errors are introduced due to differences between classical and quantum light sources and additional components are required
Solution Approach 1:
The GBS device characterizes itself by using its own quantum light sources and detectors. The squeezed light sources generate quantum states that pass through the interferometer, and the on-chip photon-number-resolving detectors measure the output, eliminating the need for external classical light sources and intensity detectors. This self-characterization approach ensures consistency between characterization and actual operation, reducing systematic errors.
Solution Approach 2:
The method extracts and removes the problematic additional components (external classical light sources and intensity detectors) from the characterization process. By eliminating these extraneous elements, the characterization uses only the intrinsic quantum light sources and detectors that are already part of the GBS device, thereby avoiding the systematic errors that arise from component mismatches.
2Ease of manufacture
If additional components are introduced for classical tomography, then characterization can be performed, but device complexity increases and efficiency decreases
Solution Approach 1:
The photon-number-resolving detectors serve dual functions: they perform the actual Gaussian Boson Sampling measurements and simultaneously enable device characterization through their ability to detect photon statistics from squeezed light sources. This multi-functionality eliminates the need for separate characterization equipment, reducing overall device complexity while maintaining characterization capability.
Solution Approach 2:
The GBS device performs its own characterization using its inherent components. The squeezed light sources and photon-number-resolving detectors that are essential for the device's primary function are repurposed for characterization, eliminating the need for additional external components and simplifying the overall system architecture.
3Measurement precision
If quantum tomography methods are used, then accurate reconstruction of quantum states is achieved, but the process requires extensive measurements on ensemble of identical states which is time-consuming
Solution Approach 1:
The method changes the parameters being measured from full quantum state tomography to specific photon statistics parameters (photon number distributions and correlation functions). By focusing on these specific parameters that are sufficient for determining the transformation matrix, the measurement process becomes more efficient while maintaining the accuracy needed for characterizing the interferometer's unitary operation.
Solution Approach 2:
Instead of performing complete quantum state tomography which requires measurements on a large ensemble of identical states, the method performs partial characterization by measuring photon statistics from squeezed light sources. This partial action is sufficient to determine the transformation matrix elements, reducing the time required while achieving the necessary characterization accuracy.
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
This approach allows for accurate in-situ characterization of GBS devices using the same kind of light as in actual experiments, reducing errors and eliminating the need for additional components, thereby providing a reliable method for determining the transformation matrices of GBS devices.
Implementation Method 1
causing activation, at a first time, of a first set of squeezed light sources from a plurality of squeezed light sources of a Gaussian boson sampling (GBS) device
Implementation Method 2
a first photon statistic is detected at a first output port from a plurality of output ports of the GBS device
Data Source
AI summary
A method includes causing activation, at a first time, of a first set of squeezed light sources from a plurality of squeezed light sources of a Gaussian boson sampling (GBS) circuit. At a second time after the first time, a first photon statistic is detected at a first output port from a plurality of output ports of the GBS circuit. At a third time after the first time, a second set of squeezed light sources from the plurality of squeezed light sources of the GBS circuit is activated, the second set of squeezed light sources being different from the first set of squeezed light sources. At a fourth time after the third time, a second photon statistic is detected at a second output port from the plurality of output ports of the GBS circuit. At least one transformation matrix is estimated that represents a linear optical interferometer of the GBS circuit based on the first photon statistic and the second photon statistic.