(a) Conventional displacement sensor circuit. H1 and H2 are persistent current switches, and leads (1) and (2) are used for current injection. (b) Magnet displacement sensor circuit.
Cell schematic. D: diaphragm (metallized), E: electrode, P: pickup coil (connected to a commercial dc SQUID outside of experimental cell), M: magnet. indicates a superfluid Josephson junction.
(a) Pickup coil can be seen at the center of black Stycast. (b) Electrode is glued onto the pickup coil.
(a) Magnet is glued to the back of a diaphragm. (b) Diaphragm is glued to the main cell piece, which houses the superfluid Josephson junction.
Displacement sensor output vs bias voltage. Solid line is a fit.
Capacitance change vs bias voltage. Solid line is a fit.
Josephson oscillation frequency at vs bias voltage applied to drive the oscillation.
Spectrum taken at with experimental cell full.
Helmholtz mode. Bias voltage is applied at . The inset shows the overall transient behavior. Data taken at . Frequency is .
Individual phase slips have been detected with the new sensor. Phase slip oscillation ends and the Helmholtz mode begins at . Data taken at .
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