PQSensing

Precision interferometry · robust quantum sensing · tabletop validation sprint

Lock the interferometer where the noise is stationary.

Noise-Stationary Locking (NSL) is a control method for Mach-Zehnder, cavity, and quantum-enhanced interferometers. Instead of locking only to a bright/dark power extremum, NSL computes a band-limited normalized noise objective and servos the operating point toward a slope-null condition.

Fund the MZI data sprint Download pitch deck
Objective: Vnorm = Nband / Pk Control target: dVnorm/dδ ≈ 0 First test: tabletop MZI

The narrow thesis

A low-cost bench test can produce the first decisive data.

Traditional locks keep an interferometer at a power-defined point. PQSensing’s thesis is that the power-defined point can be different from the noise-optimal point under real disturbance mechanisms. If a tabletop MZI shows that NSL reduces jitter-induced normalized noise compared with a conventional power lock, the resulting data becomes a credible package for licensing, SBIR/STTR, strategic partners, or investors.

Technical one-pager

Noise-Stationary Locking in one page

Problem

Interferometric sensors are fragile outside ideal lab conditions. Vibration, thermal drift, laser noise, pointing jitter, speckle, and platform motion can convert detuning error into excess measurement noise. A bright/dark power lock can remain stable while the measurement band gets noisier.

Invention

Compute a band-limited noise estimate Nband from the detector signal, compute an optical power metric P, form Vnorm = Nband/Pk, apply a small dither to the operating point δ outside the measurement band, demodulate Vnorm, and servo δ until the estimated slope approaches zero.

Why it matters

At a noise-stationary point, the first-order term in the local expansion of Vnorm(δ) is suppressed. That means detuning jitter should contribute primarily through second-order residual terms, lowering jitter-to-noise conversion in the protected band.

What gets tested first

A classical tabletop Mach-Zehnder interferometer is enough to test the core claim: sweep δ, map power and Vnorm, inject controlled jitter, compare a conventional power lock against NSL, and produce raw traces plus reproducible analysis code.

Controller objective

Vnorm(δ) = Nband(δ) / P(δ)k + power-floor penalty

Slope-null lock

e(t) ≈ LPF[Vnorm(t) · sin(2πfdt)] → 0

Validation targets

Metrics that make the first data credible

These are prototype acceptance targets, not guaranteed performance claims. They are intentionally measurable with a lean MZI build.

MetricTargetEvidence output
Power vs noise setpoint separationMeasured Vnorm stationary point differs from power extremum in at least one injected-noise regime.δ sweep, P(δ), Nband(δ), Vnorm(δ)
Jitter-induced noise reductionFirst-demo target: ≥6 dB reduction vs power lock. Stretch: 10–20 dB if bench stability supports it.Locked time traces under controlled jitter
Slope-null convergence|dVnorm/dδ| driven toward zero while maintaining P above floor.Dither/demod error signal and actuator command
Reacquisition robustness≥5 successful reacquisitions after intentional mislock / disturbance trials.State-machine log: SEARCH → CAPTURE → BIAS_LOCK → NOISE_LOCK
Optional dark-port signatureRecover known g(t) waveform by correlation/matched filtering; target ≥10 dB peak above uncorrelated disturbance.Correlation peak, lag estimate, processing-gain plot
Tabletop Mach-Zehnder-style optical bench visualization

Minimum viable experiment

The first build is deliberately classical.

No squeezed-light source is required to validate the control principle. The first milestone is a stable tabletop Mach-Zehnder with a tunable operating point, photodiode readout, controlled jitter injection, and DSP that computes Nband, P, and Vnorm in real time.

  • Measurement band: example 10 Hz–1 kHz
  • Dither frequency: outside protected band, example ~5 kHz
  • Objective exponent: k ≈ 1 for shot-noise-normalized first pass
  • Power floor: maintain signal above a minimum threshold

Roadmap

From bench data to licensing-grade IP package

  1. 0–2 weeksBench assembly

    MZI layout, photodiode readout, actuator channel, safety checks, baseline fringe.

  2. 2–4 weeksBaseline maps

    Acquire P(δ), Nband(δ), Vnorm(δ), choose k and measurement band.

  3. 4–6 weeksNSL controller

    Dither/demod error, closed-loop slope-null control, jitter injection comparison.

  4. 6–8 weeksData package

    Plots, raw logs, reproducible notebook, investor/IP outreach summary.

  5. Phase ISBIR/STTR path

    All-fiber / improved classical demonstrator; dark-port coding and Monte Carlo robustness.

  6. Phase II+Quantum + integrated photonics

    Squeezed-state integration, balanced homodyne, PIC translation, field testing, licensing.

Dark-port injection and waveform visualization

IP position

Filed around a specific control architecture.

The portfolio narrative centers on NSL and phase-controlled dark-mode injection: normalized band-limited noise objective, dither outside the protected band, power-floor penalty, mislock/reacquisition logic, dark-port waveform recovery, and quantum-enhanced variants using squeezed states and coherent receivers.

The website copy avoids over-disclosing implementation minutiae beyond the already-filed disclosure while still giving technical buyers and investors enough specificity to understand the testable wedge.

Market wedge

Robustness is the transition bottleneck.

Quantum and precision interferometric sensors are moving from lab concepts toward platform use. The near-term wedge is not “build a full product immediately”; it is produce data showing that a low-cost control layer can harden interferometric readout against nonstationary noise.

Defense PNT / ISR: GPS-denied navigation, inertial sensing, gravimetry, platform dynamics.

Metrology: optical cavities, mode cleaners, interferometric displacement and phase sensors.

LiDAR / FSOC: dark-port coding, interference rejection, correlation-based signatures.

Photonics: control algorithms for integrated MZI / PIC implementations.

Immediate ask

$10K minimum useful prototype budget

Target outcome: first credible tabletop MZI data showing whether NSL can reduce jitter-induced normalized noise compared with conventional power locking. This is the smallest useful fundraising unit: not a company-scale round, but a data sprint.

Optics and mechanics: breadboard, mirrors, beamsplitters, mounts, alignment hardware.

Readout and control: photodiode/balanced detector path, DAQ/interface, PZT/phase actuator, driver.

DSP and analysis: real-time Vnorm pipeline, dither/demod loop, reproducible notebooks.

Output: plots, raw data, deck update, outreach package for companies/investors/SBIR.

Contact PQSensing Download pitch deck

Founder

Jon Michael Peterson

Solo inventor and precision technical professional with 20+ years of hands-on engineering support, drafting, and systems problem-solving experience. The operating model is intentionally lean: use practical hardware, open-source DSP, and a sharply defined validation experiment before asking for larger capital.