Results of the HAYSTAC Phase II search for dark matter axions

16-05-2025

Significance: GS III; Science and Technology; Particle Physics;

Why in the News?

The HAYSTAC team (Phase II) recently published the paper, expressing the results of the widest search for ‘Axions’ so far. They used a special method called ‘Quantum Squeezing’ to reduce random quantum noise, making their detector more sensitive and improving their chances of finding axions.

What are Axions?

They are hypothetical elementary particles originally proposed in 1978 by Frank Wilczek and Steven Weinberg as a solution to the "strong CP problem" in Quantum Chromodynamics (QCD), which addresses why the strong nuclear force does not appear to violate certain symmetries as expected.
The ‘Axions’ has emerged in recent years as a leading particle candidate to provide the mysterious dark matter in the cosmos. The historical roots of the axion are associated within the Standard Model of particle physics and the problem of charge-parity invariance of the strong nuclear force.
The Standard Model of particle physics is still silent regarding the description of dark matter and energy, which consist of 95% of the Universe. (one of the challenge)

What is HAYSTAC?

The HAYSTAC experiment (Haloscope At Yale Sensitive To Axion Cold Dark Matter) is a collaborative initiative between Yale, Berkeley, and Johns Hopkins Universities.

Haloscope detectors like HAYSTAC are uniquely designed to search for dark matter axions in the galactic halo by detecting their conversion to microwave photons inside a resonant cavity within a strong magnetic field.

In its Phase II, HAYSTAC conducted the widest frequency search for dark matter axions to date. It introduced quantum squeezing techniques to reduce quantum noise, thereby enhancing the sensitivity of its haloscope detector.
The HAYSTAC experiment and Advanced LIGO are currently the only two major physics experiments utilising Quantum Squeezing to improve precision in measurements.

- ‘Quantum squeezing’ involves manipulating the uncertainty in quantum states to suppress random fluctuations, which improves the signal-to-noise ratio in weak signal detection, especially important for identifying rare particles like axions.

How HAYSTAC’s Haloscope Differs from Other Axion Detection Methods and is more futuristic?

Feature	HAYSTAC Haloscope Approach	Other Axio Detection
Detection Principle	Searches for axions converting into microwave photons in a strong magnetic field using a microwave cavity (haloscope).	Other methods include helioscopes (detect axions from the sun), light-shining-through-wall experiments, and astrophysical observations.
Instrument	Uses a tunable microwave cavity placed in a powerful magnetic field (haloscope).	Helioscopes use telescopes and magnets; other lab experiments use lasers or detectors for indirect effects.
Signal	Looks for resonant conversion of axions into photons at specific frequencies determined by axion mass.	Helioscopes search for X-rays from solar axions; other methods look for changes in polarization or missing energy.
Noise Reduction	Employs advanced quantum techniques like quantum squeezing to reduce quantum noise and improve sensitivity.	Most other methods do not use quantum squeezing; they rely on traditional noise reduction or background subtraction.
Frequency and Range	Tunable cavity allows scanning a wide range of possible axion masses/frequencies.	Other methods may be limited to certain energy ranges or specific axion properties.
Did you know the challenge with HAYSTAC Haloscope Approach? It requires *cryogenic temperatures* to suppress thermal noise and maximize sensitivity. While other methods do not require such maintenance of low temperature.

What are the key observations made by HAYSTAC Phase I and II?

Phases

Observations

HAYSTAC Phase I

This phase searched for dark matter axions using a microwave cavity detector operating at frequencies between 5.6 and 5.8 GHz, corresponding to axion masses in the range of approximately 23.15 to 24.0 microelectron volts.
The experiment did not detect axions, but it set new limits by excluding axion models with a two-photon coupling strength greater than about 2×10−14 GeV−1, which is about 2.7 times above the benchmark KSVZ model in this mass range.

(Technologically, it was notable for achieving near-quantum-limited sensitivity by operating at very low temperatures and using a Josephson parametric amplifier)

HAYSTAC Phase 2

No axions were detected but it set new exclusion limits on axion-photon coupling. HAYSTAC Phase II represents a significant technological and scientific advance in the search for axion dark matter, pushing the boundaries of sensitivity and experimental technique in the field of particle astrophysics.

What are the potential implications if axions are eventually detected?

Identification of Dark Matter: Axions are one of the leading candidates for dark matter. Their discovery would reveal the true nature of dark matter, which makes up about 85% of the universe’s matter content but has so far remained invisible and undetected by conventional means.
New Physics Beyond the Standard Model: Finding axions would be direct evidence of physics beyond the Standard Model, opening the door to new theories and possibly new particles or forces.
Solution to the Strong CP Problem: Detecting axions would confirm the Peccei-Quinn theory, providing a solution to the strong CP problem in quantum chromodynamics (QCD), which asks why the strong nuclear force does not violate certain symmetries as expected.
Advancements in Quantum Measurement: The techniques developed (like quantum squeezing) for axion searches could be applied to other areas of physics and quantum technology, improving the sensitivity of future experiments.
Impact on Cosmology and Astrophysics: Confirming axions as dark matter would reshape our understanding of the universe’s structure, the formation of galaxies, and the evolution of cosmic history.

PYQ Relevance:

Prelims:

In the context of modern scientific research, consider the following statements about ‘IceCube’, a particle detector located at South Pole, which was recently in the news: (UPSC CSE 2015)

1) It is the world’s largest neutrino detector, encompassing a cubic kilometre of ice.

2) It is a powerful telescope to search for dark matter

3) It is buried deep in the ice.

Which of the statements given above is/are correct?

1 only
2 and 3 only
1 and 3 only
1, 2 and 3

Mains:

Discuss the work of ‘Bose-Einstein Statistics’ done by Prof. Satyendra Nath Bose and show how it revolutionized the field of Physics. (UPSC CSE 2018)
The Nobel Prize in Physics of 2014 was jointly awarded to Akasaki, Amano and Nakamura for the invention of Blue LEDs in 1990s. How has this invention impacted the everyday life of human beings? (UPSC CSE 2022)

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Results of the HAYSTAC Phase II search for dark matter axions

Results of the HAYSTAC Phase II search for dark matter axions