The Superfluid 4 He Analog of the RF SQUID
نویسنده
چکیده
This paper describes a superfluid analog of the superconducting RF SQUID.1 Whereas an RF SQUID is sensitive to magnetic flux, the 4He SQUID (Superfluid QUantum Interference Device) is sensitive to absolute rotation. The device described here exhibits several of the characteristic phenomena of SQUIDs. For example: There is a "staircase" response function. The slope of the staircase response is determined by the fluctuation phenomena underlying phase slips in a weak link. The device performance is sensitive to the uncontrolled motion of quantized vortices. Performance is adversely affected by the excitation of normal modes of the device. Fundamental fluctuations, thermal in this case, determine the noise floor of the device. The theory describing the 4He SQUID rests on the very foundation of the theory of superfluidity in 4He.2 The state of superfluid 4He is described by a macroscopic wave function whose phase, O, is proportional to the superfluid velocity potential:
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