Principles of superfluid-helium gyroscopes

Abstract

In this paper we desribe how quantum coherence of superfluid helium provides a mechanism by which very small rotations can substantially modify the flow in a toroidal container. The specific modifications to that flow are discussed. For He, we explain how the rotationally induced flow can be detected by monitoring the apparent phase-slip critical current. The rotational resolution is limited by stochastic processes related to the nucleation of phase slips. This type of superfluid-helium gyroscope (SHEG) is an analog of the rf superconducting quantum interference device (SQUID). We also show how the large coherence length of 'He can be utilized to lead to a rotationally induced interference pattern. Changes in this pattern can permit the detection of very small rotational motion. This type of SHEG is analogous to the dc SQUID. In appendixes, electrical circuits equivalent to the SHEG are described, as are certain constraints on rotational sensitivity imposed by external measuring devices.

Detection of the Rotation of the Earth with a Superfluid Gyrometer

“…This convergence of points of view can also be justified, as noted by a number of authors [7,8,10], by the analogy between charged and neutral superfluids. As discussed by Nozières [14], a rotation field 2 V applied to a toroidal container of helium can be viewed as analogous to a magnetic field B applied to a superconducting annulus, the rotation induced velocity V 3 r as analogous to the vector potential A 1 2 B 3 r, and the quantization of the circulation of y 0 s 2 V 3 r corresponding to that of the fluxoid [15].…”

“…Interferometric techniques exploiting the wave-mechanical nature of light beams-the Sagnac effect [2]-of neutron [3] and electron [4] beams have been devised in order both to demonstrate the general laws of inertia and to improve gyrometric techniques [5]. We describe below an experiment [6] which has been considered by a number of authors [7][8][9][10][11] and in which the effect of V © on a loop of superfluid 4 He is measured with the help of quantum phase slippage [12] to a resolution of better than 10 22 .…”

SuperfluidHe4interferometer operating near2K

“…2 by the smallest detectable current, -7 rad/sec in a one Hertz bandwidth. Although analysis' of the thermal noise limits of related devices have been performed 11,12 , the corresponding limit for our device is not yet known. We are currently limited by the random rocking motion of our air spring cryostat support system, which creates nuisance rotation signals approximately one order of magnitude greater than the electronic background.…”

dc Supercurrents from Resonant Mixing of Josephson Oscillations in aH3eWeak Link

“…For example, since the dc current at the peak scales with I 2 c , the peak current could be used as the physical observable in a quantum interference device such as a 3 He dc-SQUID [13]. Also, a feedback mechanism which maintains the DI at its maximum value may provide a very precise pressure standard via Eq.…”