Microwave resonator for measuring time-reversal symmetry breaking at cryogenic temperatures
Bibliographic record
Abstract
We present a microwave-frequency method for measuring the polar Kerr effect and spontaneous time-reversal symmetry breaking (TRSB) in unconventional superconductors. While this experiment is motivated by work performed in the near infrared using zero-loop-area Sagnac interferometers, the microwave implementation is quite different and is based on the doubly degenerate modes of a TE111 cavity resonator, which act as polarization states analogous to those of light. The resonator system has in situ actuators that allow quadrupolar distortions of the resonator shape to be controllably tuned, as these compete with the much smaller perturbations that arise from TRSB. The most reliable way to detect the TRSB signal is by interrogating the two-mode resonator system with circularly polarized microwaves, in which case the presence of TRSB shows up unambiguously as a difference between the forward and reverse transmission responses of the resonator-i.e., as a breaking of reciprocity. We illustrate and characterize a coupler system that generates and detects circularly polarized microwaves and then show how these are integrated with the TE111 resonator, resulting in a dilution refrigerator implementation with a base temperature of 20 mK. We show test data on yttrium-iron-garnet ferrite and the van der Waals ferromagnet CrGeTe3 as an illustration of how the system operates. We then present data showing system performance under realistic conditions at millikelvin temperatures, achieving a Kerr-angle resolution δθK = 810 nrad for a 2 × 2 mm2 sample, approaching the resolution of an optical Sagnac interferometer.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".