Truncated nonlinear interferometer-based sensor system
Inventors
Pooser, Raphael C. • Lawrie, Benjamin J. • Maksymovych, Petro
Assignees
Publication Number
US-12181773-B2
Publication Date
2024-12-31
Expiration Date
2039-12-18
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Abstract
A truncated non-linear interferometer-based sensor system includes an input port that receives an optical beam and a non-linear amplifier that amplifies the optical beam with a pump beam and renders a probe beam and a conjugate beam. The system's local oscillators have a relationship with the respective beams. The system includes a sensor that transduces an input with the probe beam and the conjugate beam or their respective local oscillators. It includes one or more phase-sensitive detectors that detect a phase modulation between the respective local oscillators and the probe beam and the conjugate beam. Output from the phase-sensitive-detectors is based on the detected phase modulation. The phase-sensor-detectors include measurement circuitry that measure the phase signals. The measurement is the sum or difference of the phase signals in which the measured combination exhibit a quantum noise reduction in an intensity difference or a phase sum or an amplitude difference quadrature.
Core Innovation
The invention discloses a truncated non-linear interferometer (NLI)-based sensor system that includes an input port for receiving an optical beam, a non-linear amplifier that amplifies the optical beam with a pump beam to produce a probe beam and a conjugate beam, and a set of local oscillators having a relationship with those beams. The system features phase-sensitive detectors that detect phase modulation between the respective local oscillators and the probe and conjugate beams, producing outputs indicative of the measured phase modulation. Measurement circuitry is configured to process the output, measuring either the sum or difference of the detected phase signals, which exhibit quantum noise reduction in an intensity difference, phase sum, or amplitude difference quadrature.
The problem addressed by this invention is that conventional atomic force microscopes (AFMs) and related interferometric sensors are limited by the standard quantum limit, with performance degraded by losses between the signal transduction point and detection, as well as by noise sources including thermal noise, backaction noise, and photon shot noise. In particular, backaction noise restricts available readout power, and the need to operate AFMs at cantilever resonance for improved signal leads to narrow bandwidth and slow measurements due to micromechanical ring down effects.
The disclosed truncated NLI sensor systems utilize phase detection after nonlinear amplification to achieve enhanced dynamic range, quantum-enhanced phase measurements, and higher signal-to-noise ratios than linear interferometer-based systems. The design enables compensation for spatial mode fluctuations and nonuniform spatial modes, maintaining high interference visibility and practicality. The combination of quantum noise reduction, improved SNR through large local oscillator powers, and dual phase measurements supports new broadband, high-speed scanning probe microscopy approaches, including measuring cantilever probe displacements with quantum noise reduction bounded only by amplifier gain and system loss.
Claims Coverage
The patent presents two independent claims, each introducing a distinct inventive feature in truncated non-linear interferometer-based sensor systems and methods of their operation.
Truncated non-linear interferometer-based sensor system with phase-sensitive detection and quantum noise reduction
The system comprises: - An input port for receiving an optical beam. - A non-linear amplifier that processes the input optical beam with a pump beam to generate a probe beam and a conjugate beam. - Local oscillators that have a measurable relationship with the probe and conjugate beams. - A sensor whose input is transduced by the probe beam, conjugate beam, or their local oscillators as a phase change. - One or more phase-sensitive detectors configured to detect a phase modulation between the local oscillators and the probe and conjugate beams, providing phase signals based on detected phase modulation. - Measurement circuitry capable of measuring combinations (sum or difference) of phase signals that indicate the sensor's input, where the measured signals display quantum noise reduction in an intensity difference, phase sum, or amplitude difference quadrature.
Method for quantum noise reduction sensing in a truncated non-linear interferometer-based sensor system
The method consists of: 1. Coupling an optical beam to a non-linear amplifier for amplification with a pump beam to yield a probe beam and a conjugate beam. 2. Generating two local oscillators that have a measurable relationship with, and are phase-locked to, the probe and conjugate beams. 3. Inducing a phase shift in the probe or conjugate beam or their associated local oscillators by coupling to a sensor, with the sensor's input being transduced into the phase shift. 4. Detecting, via one or more phase-sensitive detectors, the phase modulation between the respective local oscillators and the probe or conjugate beams; the detected phase modulation corresponding to the phase shift is output as one or more phase signals. 5. Measuring the sum and difference of the phase signals, resulting in signals that exhibit quantum noise reduction in either an intensity difference, phase sum, or amplitude difference quadrature.
These inventive features claim a truncated non-linear interferometer-based sensor system and methods that provide quantum-enhanced sensing via phase modulation detection, enabling improved signal-to-noise ratio and dynamic range through quantum noise reduction and flexible phase-sensitive detection architectures.
Stated Advantages
Outperforms linear interferometer-based sensor systems by achieving enhanced dynamic range, quantum-enhanced phase measurements, and higher signal-to-noise ratios.
Minimizes photon backaction noise and photon shot noise simultaneously through the use of squeezed states and high-power local oscillators in phase-sensitive detection.
Automatically compensates for spatial mode fluctuations or nonuniform spatial modes while maintaining high interference visibility, improving sensor practicality.
Enables faster, broadband, high-speed scanning probe microscopy without requiring operation at cantilever resonance frequency.
Facilitates quantum-enhanced beam displacement measurements with sub shot noise sensitivity and reduced loss compared to conventional sensors.
Can achieve greater than two orders of magnitude improvement in signal-to-noise ratio compared with conventional interferometric AFMs.
Allows for increased scalability by enabling parallel readout of multiple cantilevers when multiple spatial modes are generated.
Documented Applications
Atomic force microscope (AFM) configured with a truncated non-linear interferometer-based sensor system to measure cantilever displacements with quantum-enhanced noise reduction.
Sensor systems for plasmonic or metamaterial sensors utilizing quantum noise reduction and phase-sensitive detection.
Magnetometer applications where sensor input is transduced into phase shifts in the probe and conjugate beams for quantum-enhanced measurement.
Imaging sensors that leverage quantum noise reduction via a truncated NLI configuration for enhanced sensitivity.
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