Spin is one of the most fundamental quantum properties of particles. In this talk I will describe our experimental studies of “spin-helical” particles (analogous to neutrinos with spin locked to the momentum, but for electrons and atoms) as a powerful platform to realize novel quantum matter and enable new applications in quantum technologies — such quantum information, quantum energy, quantum chemistry and quantum simulation. For example, we have demonstrated spin-helical electrons [1,2] on the surface of “topological insulators” (TI) and discovered a “topological spin battery” [3], opening the possibility to electrically induce and readout a nuclear and electronic spin polarization with exceptionally long lifetime — which we present as a remarkable demonstration of the “topological protection” unique to TI. We further observe unusual behaviors in superconducting Josephson junctions and SQUIDs made out of our TIs [4,5], paving the way for using such spin-helical electrons to realize “topological superconductor” proposed to harbor “majorana fermions” that could enable scalable, topologically- protected quantum computing. Using light-matter interaction to engineer “synthetic” spin orbit coupling and gauge fields on laser-cooled 87Rb atoms, we realize spin-helical bosons in a Bose-Einstein condensate (BEC), where we can dynamically control the Hamiltonian and perform various quantum transport, interferometry, chemistry, and even “collider” experiments. We demonstrate a new “interferometric”approach for quantum control of chemical reactions by preparing reactants in spin superpositions [6]. The system could also be used as a quantum simulator to study phenomena ranging from spin decoherence in interacting systems [7] to novel quantum matter in extra “synthetic” dimensions or curved spaces not easily realized in electronic materials [8].

Yong P. Chen leads the “Quantum Matter and Devices Laboratory” that makes, measures and manipulates diverse quantum matter ranging from 2D/topological/hybrid quantum materials to atomic quantum gases, with potential applications such as energy, sensing, and quantum technologies. He received a BS and MS in mathematics from Xi’an Jiaotong University and MIT, a Ph.D. in electrical engineering from Princeton University, and did a physics postdoc at Rice University. He joined Purdue faculty in 2007 and is currently Professor of Physics and Electrical and Computer Engineering as well as the Associate Director of Research for Birck Nanotechnology Center, and the Inaugural Director of Purdue Quantum Science and Engineering Institute (PQSEI). He is a recipient of (young) faculty awards from NSF, DOD, ACS, IBM, and Horiba Award, a Fellow of American Physical Society, a principal investigator in WPI-AIMR International Materials Research Center in Japan, and selected as a Villum Investigator in Denmark.<.p>

Purdue Quantum Science and Engineering Institute, Discovery Park

1. J.Tian et al. "Electrical injection and detection of spin-polarized currents in topological insulator Bi2Te2Se", Sci. Rep. 5, 14293 (2015);
2. J. Tian et al., “On the understanding of current-induced spin polarization of three- dimensional topological insulators”, Nature Comm. 10, 1461 (2019);
3. J.Tian et al., "Observation of current-induced, long-lived persistent spin polarization in a topological insulator: a rechargeable spin battery", Science Advances 3, e1602531 (2017);
4. M.Kayyalha et al., "Anomalous low-temperature enhancement of supercurrent in topological- insulator nanoribbon Josephson junctions: evidence for low-energy Andreev bound states", PRL 122, 047003 (2019);
5. M.Kayyalha et al., "Highly skewed current-phase relation in superconductor-topological insulator-superconductor Josephson junctions", arXiv:1812.00499;
6. D.Blasing et al. "Observation of Quantum Interference and Coherent Control in a Photo-Chemical Reaction", PRL 121, 073202 (2018);
7. C. Li et al."Spin Current Generation and Relaxation in a Quenched Spin-Orbit Coupled Bose-Einstein Condensate", Nature Comm. 10, 375 (2019);
8. C.Li et al., "A Bose-Einstein Condensate on a Synthetic Hall Cylinder", arXiv:1809.02122

Researchers should cite this work as follows:

• Yong P. Chen (2019), "Spin-Helical Particles: an Enabling Platform for Quantum Matter and Quantum Technologies," https://nanohub.org/resources/30722.

  BibTex | EndNote

1. Bose-Einstein condensate
2. chemistry
3. Fermions
4. quantum chemistry
5. quantum materials
6. spin-helical particles
7. SQUIDs