Quantum sensing

Advancing astrophysics with single-photon detection

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NASA Jet Propulsion Laboratory (JPL), USA

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Case studyProduct: PrestoProduct: Metronomo

Summary

Challenge: NASA’s Jet Propulsion Laboratory (JPL) needed to characterize complex Single Photon Detectors (SPDs)—specifically Quantum Capacitance Detectors (QCDs) and Hybrid KID-QCDs—which require high-sensitivity measurements to detect fundamental light particles.

Solution: The research team created a synchronized measurement cluster using three Presto units timed by a Metronomo.

Outcome: Using the Lockin measurement mode, the setup enabled the simultaneous readout of 441 single photon detectors, successfully identifying single-photon events and establishing a pathway for further scaling.
Figure 1

Image adapted from [Pierre Echternach, 2024, "A Hybrid Quantum Capacitance-Kinetic Inductance Detector"](https://doi.org/10.48577/jpl.OZ79YC). 3 Presto units are synchronized using a Metronomo to readout 441 single photon detectors using the Lockin mode. On the right, the acquired quadrature data (a), and processed data (b) and (c) where red circles indicate the detection of a single photon.

Advancing astrophysics with single-photon detection

Dr. Pierre Echternach and the team at NASA's Jet Propulsion Laboratory (JPL) is currently developing advanced sensors intended for the next generation of space exploration and scientific research. A primary focus of this initiative is the development of Single Photon Detectors (SPD)—sensors capable of detecting the fundamental particles of light.

The research focuses on two specific detector architectures:

  • Quantum Capacitance Detectors (QCDs)
  • Hybrid Kinetic Inductance-Quantum Capacitance Detectors (Hybrid KID-QCD)

Technology Overview: How QCDs Work
QCDs operate using a superconducting island connected to a ground electrode via a tunnel junction. The detection mechanism relies on the behavior of Cooper pairs (paired electrons). When a photon strikes the detector, it breaks these pairs, creating quasiparticles (unpaired electrons).

These quasiparticles tunnel onto the island, resulting in a distinct change in capacitance. To measure this, the QCD is embedded in a resonator; the shift in capacitance alters the resonance frequency, which can then be detected. While standard QCDs offer high sensitivity, they historically present a limited dynamic range.

To address this, JPL is developing a Hybrid KID-QCD sensor. This architecture combines the high sensitivity of QCDs with the broader dynamic range of Kinetic Inductance Detectors (KIDs), allowing for accurate measurements over a wider range of optical powers.

The Measurement Solution
To validate the performance of these sensors, the research required instrumentation capable of analyzing raw quadrature response with extreme precision and an ability to multiplex many frequencies while preserving phase coherence between the output tones and the demodulated reference signals.

The experiment utilized a scalable setup consisting of three Presto microwave units synchronized by a Metronomo. By utilizing Lockin mode, the team achieved the simultaneous readout of 441 single photon detectors. This configuration allowed for the precise measurement of quantum capacitance and the identification of single-photon detection events across the array.

Scaling for the Future: Spectral Mode
A significant hurdle in SPD research is the ability to scale from testing hundreds of sensors to measuring large-scale arrays. To facilitate this scaling, Intermodulation Products has introduced a new measurement mode known as Spectral.

While the Lockin mode handles high-precision readout of hundreds of sensors per unit (as demonstrated by the 441 detectors in this study), the Spectral mode is designed to enable the measurement of thousands of sensors using a single Presto unit. This development aims to significantly enhance the throughput of SPD characterization, supporting their eventual deployment in astrophysics and broader scientific applications.

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