Rowland Institute at Harvard

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SATO LAB

Rowland Institute at Harvard

Harvard University

By placing two (and more) “weak links” in a loop of superfluid helium as in a dc-SQUID, a unique matter wave interferometer can be realized. We have constructed and used such interference devices for rotation sensing through Sagnac effect, measurement of quantum phase gradient associated with superfluid flow, detection of quantized vortex line motion, and construction of an absolute gauge for quantum mechanical phase shifts. We are working on further developing our matter wave interferometers to investigate novel interactions that give rise to quantum phase shifts in a neutral matter system. By taking advantage of the macroscopic coherent nature of our superfluid system, we are developing more sensitive and more practical superfluid gyroscope to contribute to fields such as seismology, geodesy, inertial navigation, and general relativity. With an asymmetric interference grating, we are also using superfluid as a test bed for studying the formation of topological defects and second order phase transitions.

Superfluid quantum interference in multiple-turn reciprocal geometry

We report the observation of superfluid quantum interference in a compact, large area matter-wave interferometer consisting of a multiple-turn interfering path in reciprocal geometry. Utilizing the Sagnac effect from the Earth’s rotation in conjunction with a phase shifter made of superfluid heat current, we demonstrate that such a scheme can be extended for sensitive rotation sensing as well as for general interferometry.

Physical Review Letters 106, 255301 (2011).

Fiske-amplified superfluid interferometry

We report an experimental demonstration of signal amplification for a superfluid 4He interferometer by allowing the matter waves from two Josephson mass current sources to interact with the resonances within the experimental cell. We characterize the interferometer using an external phase shift and demonstrate a thirty-fold enhancement in intrinsic phase sensitivity.

Physical Review B 81, 172502 (2010).

Review on superfluid helium quantum interference devices

In a review article titled “Superfluid helium quantum interference devices: physics & applications”, Y. Sato and R. Packard describe recent developments in the field of superfluid Josephson phenomena and quantum interference devices.

Reports on Progress in Physics 75, 016401 (2012).