Superfluidity is a quantum state of matter that exists macroscopically in helium at low temperatures. The elementary excitations in superfluid helium have been probed with great success using techniques such as neutron and light scattering. However, measurements of phonon excitations have so far been limited to average thermodynamic properties or the driven response far out of thermal equilibrium. Here, we use cavity optomechanics to probe the thermodynamics of phonon excitations in real time. Furthermore, strong light–matter interactions allow both laser cooling and amplification. This represents a new tool to observe and control superfluid excitations that may provide insight into phonon–phonon interactions, quantized vortices and two-dimensional phenomena such as the Berezinskii–Kosterlitz–Thouless transition. The third sound modes studied here also offer a pathway towards quantum optomechanics with thin superfluid films, including the prospect of femtogram masses, high mechanical quality factors, strong phonon–phonon and phonon–vortex interactions, and self-assembly into complex geometries with sub-nanometre feature size.
Subscribe to Journal
Get full journal access for 1 year
only $14.08 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Hoffmann, J. A., Penanen, K., Davis, J. C. & Packard, R. E. Measurements of attenuation of third sound: evidence of trapped vorticity in thick films of superfluid He-4. J. Low Temp. Phys. 135, 177–202 (2004).
Ellis, F. M. & Luo, H. Observation of the persistent-current splitting of a 3rd-sound resonator. Phys. Rev. B 39, 2703–2706 (1989).
Barenghi, C. F., Skrbek, L. & Sreenivasan, K. R. Introduction to quantum turbulence. Proc. Natl Acad. Sci. USA 111, 4647–4652 (2014).
Bishop, D. J. & Reppy, J. D. Study of the superfluid transition in two-dimensional films. Phys. Rev. Lett. 40, 1727–1730 (1978).
Tilley, D. & Tilley, J. Superfluidity and Superconductivity (CRC, 1990).
Bramwell, S. T. & Keimer, B. Neutron scattering from quantum condensed matter. Nature Mater. 13, 763–767 (2014).
Pike, E. R., Vaughan, J. M. & Vinen, W. F. Brillouin scattering from superfluid He-4. J. Phys. C 3, L40 (1970).
Fonda, E., Meichle, D. P., Ouellette, N. T., Hormoz, S. & Lathrop, D. P. Direct observation of Kelvin waves excited by quantized vortex reconnection. Proc. Natl Acad. Sci. USA 111, 4707–4710 (2014).
Brooks, J. S., Ellis, F. M. & Hallock, R. B. Direct observation of third-sound mass displacement waves in unsaturated superfluid films. Phys. Rev. Lett. 40, 240–243 (1978).
De Lorenzo, L. A. & Schwab, K. C. Superfluid optomechanics: coupling of a superfluid to a superconducting condensate. New J. Phys. 16, 113020 (2014).
Aspelmeyer, M., Kippenberg, T. J. & Marquardt, F. Cavity optomechanics. Rev. Mod. Phys. 86, 1391–1452 (2014).
Bowen, W. P. & Milburn, G. Quantum Optomechanics (CRC, 2016).
Palomaki, T. A., Teufel, J. D., Simmonds, R. W. & Lehnert, K. W. Entangling mechanical motion with microwave fields. Science 342, 710–713 (2013).
Brooks, D. W. C. et al. Non-classical light generated by quantum-noise-driven cavity optomechanics. Nature 488, 476–480 (2012).
Verhagen, E., Deleglise, S., Weis, S., Schliesser, A. & Kippenberg, T. J. Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode. Nature 482, 63–67 (2012).
Riedinger, R. et al. Non-classical correlations between single photons and phonons from a mechanical oscillator. Nature 530, 313–316 (2016).
Wollman, E. E. et al. Quantum squeezing of motion in a mechanical resonator. Science 349, 952–955 (2015).
Pirkkalainen, J.-M., Damskägg, E., Brandt, M., Massel, F. & Sillanpää, M. Squeezing of quantum noise of motion in a micromechanical resonator. Phys. Rev. Lett. 115, 243601 (2015).
Lecocq, F., Clark, J., Simmonds, R., Aumentado, J. & Teufel, J. Quantum nondemolition measurement of a nonclassical state of a massive object. Phys. Rev. X 5, 041037 (2015).
Metcalfe, M. Applications of cavity optomechanics. Appl. Phys. Rev. 1, 031105 (2014).
Krause, A. G., Winger, M., Blasius, T. D., Lin, Q. & Painter, O. A high-resolution microchip optomechanical accelerometer. Nature Photon. 6, 768–772 (2012).
Forstner, S. et al. Ultrasensitive optomechanical magnetometry. Adv. Mater. 26, 6348–6353 (2014).
Agarwal, G. S. & Jha, S. S. Theory of optomechanical interactions in superfluid He. Phys. Rev. A 90, 023812 (2014).
Penanen, K. & Packard, R. E. A model for third sound attenuation in thick He-4 films. J. Low Temp. Phys. 128, 25–35 (2002).
Armani, D. K., Kippenberg, T. J., Spillane, S. M. & Vahala, K. J. Ultra-high-Q toroid microcavity on a chip. Nature 421, 925–928 (2003).
Atkins, K. R. Third and fourth sound in liquid helium ii. Phys. Rev. 113, 962–965 (1959).
Shirron, P. J. & Mochel, J. M. Atomically thin superfluid-helium films on solid hydrogen. Phys. Rev. Lett. 67, 1118–1121 (1991).
Anetsberger, G. et al. Near-field cavity optomechanics with nanomechanical oscillators. Nature Phys. 5, 909–914 (2009).
Harris, G. I., Andersen, U. L., Knittel, J. & Bowen, W. P. Feedback-enhanced sensitivity in optomechanics: surpassing the parametric instability barrier. Phys. Rev. A 85, 061802 (2012).
Riviere, R., Arcizet, O., Schliesser, A. & Kippenberg, T. J. Evanescent straight tapered-fiber coupling of ultra-high Q optomechanical micro-resonators in a low-vibration helium-4 exchange-gas cryostat. Rev. Sci. Instrum. 84, 043108 (2013).
McAuslan, D. L. et al. Microphotonic forces from superfluid flow. Preprint at http://arxiv.org/abs/1512.07704 (2015).
Meenehan, S. M. et al. Silicon optomechanical crystal resonator at millikelvin temperatures. Phys. Rev. A 90, 011803 (2014).
Restrepo, J., Gabelli, J., Ciuti, C. & Favero, I. Classical and quantum theory of photothermal cavity cooling of a mechanical oscillator. C. R. Phys. 12, 860–870 (2011).
Jourdan, G., Comin, F. & Chevrier, J. Mechanical mode dependence of bolometric backaction in an atomic force microscopy microlever. Phys. Rev. Lett. 101, 133904 (2008).
Bustamante, C., Liphardt, J. & Ritort, F. The nonequilibrium thermodynamics of small systems. Phys. Today 58, 43–48 (July, 2005).
Simula, T., Davis, M. J. & Helmerson, K. Emergence of order from turbulence in an isolated planar superfluid. Phys. Rev. Lett. 113, 165302 (2014).
Kozik, E. & Svistunov, B. Vortex-phonon interaction. Phys. Rev. B 72, 172505 (2005).
Davis, S. I., Hendry, P. C. & McClintock, P. V. E. Decay of quantized vorticity in superfluid 4He at mK temperatures. Physica B 280, 43–44 (2000).
Kosterlitz, J. M. & Thouless, D. J. Ordering, metastability and phase transitions in two-dimensional systems. J. Phys. C 6, 1181–1203 (1973).
This research was funded by the Australian Centre for Engineered Quantum Systems (CE110001013). Micro-fabrication was performed at the Queensland Node of the Australian National Fabrication Facility (ANFF-Q). W.P.B. was supported by the ARC Future Fellowship FT140100650. The authors thank G. A. Brawley, M. J. Davis, B. J. Powell and Z. Duan for valuable discussions.
The authors declare no competing financial interests.
About this article
Cite this article
Harris, G., McAuslan, D., Sheridan, E. et al. Laser cooling and control of excitations in superfluid helium. Nature Phys 12, 788–793 (2016). https://doi.org/10.1038/nphys3714
Optics Express (2020)
Nature Physics (2020)
Physical Review A (2020)
Laser & Photonics Reviews (2020)
Physical Review Research (2020)