Quantum-State Modal Measurement Using Electro-Optic Pulse Modulation
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Solution Overview
Problem
Existing systems for performing two-time correlation measurements on quantum light sources are limited by interferometer arm length variations, restricting the range of measurements that can be made, particularly for quantum states lasting several nanoseconds.
Innovation Solution
A system utilizing a pulsed homodyne tomography setup with a quantum light source, a local pulse train generator, and a homodyne detector, employing an arbitrary wave generator to control electrical waveforms for modulating local optical pulses, enabling broader two-time correlation measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an interferometer is used to generate local optical pulses for two-time correlation measurements, then the measurement setup is established, but the time delay range is limited by interferometer arm length variations
Solution Approach 1:
The patent replaces the mechanical interferometer-based delay control with an electro-optic modulator system. The electro-optic modulator uses electrical signals to control the phase and amplitude of local optical pulses, enabling precise time delay control without mechanical movement. This substitution resolves the contradiction by providing both measurement precision and extended adaptability in time delay range.
Solution Approach 2:
The patent introduces dynamic control of local optical pulse generation through electro-optic modulators that can be adjusted in real-time. The system allows continuous variation of time delays between local pulses and the optical pulse of interest, enabling adaptation to different quantum state durations (from picoseconds to nanoseconds) while maintaining measurement precision.
2Adaptability or versatility
If the interferometer arm length is changed to measure quantum states lasting several nanoseconds, then the measurement range is extended, but the physical length variation required (at least 30 cm) becomes impractical
Solution Approach 1:
The patent replaces mechanical adjustment of interferometer arm lengths with electro-optic modulation. The electro-optic modulator changes the optical properties (phase, amplitude) of local pulses through electrical control, achieving the same functional effect as mechanical length changes without requiring physical space. This allows measurement of quantum states from picoseconds to nanoseconds duration without impractical mechanical adjustments.
3Reliability
If traditional interferometer systems are used for two-time correlation measurements, then the basic measurement function is achieved, but the system cannot effectively probe quantum states with durations requiring large time delays
Solution Approach 1:
The patent creates a universal measurement system using electro-optic modulators that can handle multiple quantum state types and durations through electrical programming. The same basic setup can measure picosecond-pulsed quantum states, nanosecond quantum states, or continuous quantum states by simply changing the electrical control signals to the modulators, maintaining measurement accuracy across all applications.
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 accurate determination of modal properties of quantum states with extended measurement ranges, allowing for precise reconstruction of quantum states without prior knowledge of their characteristics.
Implementation Method 1
a homodyne detector optically coupled to the quantum light source and to the local pulse train generator, the homodyne detector performing two-time correlation measurements between the given optical pulse and the train of local optical pulses
Implementation Method 2
an optical modulator optically coupled to the laser source and modulating the local optical signal... an arbitrary wave generator electrically coupled to the optical modulator and supplying electrical waveforms to the optical modulator for said modulating
Data Source
AI summary
There is described a system for determining a modal property of a quantum state. The system generally has a quantum light source generating an optical pulse having a given frequency, a pulse time duration and a quantum state with a modal property; a local pulse generator having: a laser source generating a local optical signal having a frequency associated to the given frequency; an optical modulator modulating the local optical signal; and an arbitrary wave generator supplying electrical waveforms to the optical modulator for said modulating, said modulating including forming local optical pulses from the local optical signal, the local optical pulses being distributed within the pulse time duration; and a homodyne detector optically coupled to the quantum light source and to the local pulse generator for performing two-time correlation measurements being indicative of the modal property of the quantum state of the given optical pulse.