This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
This award will provide partial support for the completion of Harvard's helium recovery and reliquefaction infrastructure . The project includes helium gas recovery piping from a multi-user nuclear magnetic resonance facility and from the labs of 15 faculty members (8 physics, 3 engineering, and 4 chemistry), and the fixed equipment to collect, liquefy, and dispense the recovered helium. The project would also include HVAC, electrical, and control infrastructure required for operation.
Helium is used extensively in physics, engineering, chemistry, and biology research whenever cold environments are needed for experiments or detectors. Current and future research activities include making accurate measurement of the electron magnetic moment and the fine structure constant, and the most stringent test of charge-parity-time symmetry with leptons; using helium as a buffer gas to cool new atoms and molecules into Bose-Einstein condensates and quantum Fermionic systems; providing cooling for studies of the electronic orders in exotic correlated electron materials such as high-Tc superconductors and graphene; allowing access to the quantized energy levels in nanostructures fabricated from materials such as GaAs, carbon nanotubes, graphene, and diamond; and permitting diagnostics such as nuclear magnetic resonance, Mossbauer spectroscopy, and scanning tunneling spectroscopy of newly synthesized molecules and catalysts.
Each year, over 300 students and postdocs will be working on research projects in physics, chemistry, and materials science that involve liquid helium. The liquefier would conserve helium, a precious nonrenewable resource, and would consume approximately one-fifth the electricity of alternative technologies such as pulse tube refrigerators.
With funding from the NSF under grant AST-0963347, Harvard University constructed a helium recovery and liquefier facility, which has now been fully operational since May 2, 2013. A labeled photograph of the facility is shown in Fig. 1. Intellectual merit: Fundamental scientific understanding of our world, as well as technological applications to improve human lives, often require experiments at very low temperatures, achievable exclusively through the use of liquid helium. In fact, 16 Nobel Prizes in physics and chemistry since 1970 have been enabled by liquid helium. However, helium is a limited resource on our planet, whose commercial price has nearly tripled in the last decade. The completion of a system to recover the helium gas boiloff before it disperses and eventually escapes the earth’s gravity, and to reliquefy it on site at Harvard, preserves this precious resource, and allows scientists in the physics, chemistry, engineering and applied sciences departments to carry out their fundamental and applied research at less than half the commercial cost. In the seven months since Harvard has been recovering and delivering 50%-discounted helium, at least seven research groups have been able to increase the efficiency of their research. A few specific examples of research achievements enabled by Harvard’s new supply of recovered and reliquefied helium follow. The Hoffman lab has used the new helium supply to cool a scanning tunneling microscope to image SmB6 with atomic resolution (Fig. 2), finding evidence that the material is a "topological Kondo insulator" – a material with insulating interior but metallic surface which could be useful in future spintronics devices [1]. The Westervelt lab is also using helium to cool a scanning probe microscope, to image electron flow in graphene. The Yacoby lab used helium to measured Josephson supercurrents through HgTe quantum wells, confirming that this material possesses one-dimensional edge channels that could be used to generate a new type of topological superconductivity [2]. The Lukin lab used helium to investigate nitrogen-vacancy centers – a possible route to quantum computing and high-resolution magnetic imaging [3]. The Gabrielse group used helium to test the operation of a new superconducting magnet which will be used to trap antihydrogen. The Silvera group has used helium in two experiments, to search for metallic hydrogen, and to measure the electric dipole moment of the neutron. Broader impact: As of December 2013, Harvard has recovered 8,667 liters of liquid helium, representing the preservation of a non-renewable resource, as well as total savings over $55,000. The current recovery rate is 75%, and still climbing as research groups learn to maximize their efficiency. The current rate of savings could allow the employment and education of at least four extra graduate students per year, in addition to more than 40 existing graduate students and postdocs who have benefitted directly from the efficient use of helium in their research and education over the last seven months. Additionally, in the spirit of the American Recovery and Reinvestment Act through which this grant was funded, the construction of the recovery and liquefier system provided approximately 80 person-months of American employment during the construction phase, and has resulted in two full-time jobs at Harvard for the foreseeable future. Publications [1] M. M. Yee, Y. He, A. Soumyanarayanan, D.-J. Kim, Z. Fisk, J. E. Hoffman, "Imaging the Kondo Insulating Gap on SmB6," Arxiv Preprint 1308.1085 (2013). [2] Sean Hart, Hechen Ren, Timo Wagner, Philipp Leubner, Mathias Mühlbauer, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp, Amir Yacoby, "Induced Superconductivity in the Quantum Spin Hall Edge." (in preparation) [3] Y. Chu, N.P. de Leon, B.J. Shields, B. Hausmann, R. Evans, E. Togan, M. J. Burek, M. Markham, A. Stacey, A.S. Zibrov, A. Yacoby, D.J. Twitchen, M. Loncar, H. Park, P. Maletinsky, M.D. Lukin, "Coherent optical transitions in implanted nitrogen vacancy centers." (submitted)
