David W Snoke

  • Distinguished Professor
G10 Allen Hall
snoke@pitt.edu
http://www.snokelab.com

Research

Our experimental group uses a wide array of optical methods to study fundamental questions of quantum mechanics in semiconductor systems. Our optical methods include ultrafast spectroscopy on femtosecond and picosecond time scales, time-resolved interferometry, real-space and momentum space (Fourier) imaging with CCD cameras, and nonlinear optics such as two-photon absorption and the optical Stark effect. We can also apply variable stress to samples to create potential gradients to move particles inside solids, vary temperature down to cryogenic temperatures, and measure transport with electronics.

One of the main efforts in our lab at present in the study of polariton condensates in microcavities. Polaritons are essentially photons dressed with an effective mass and repulsive interactions due to the special design of the solid-state microcavity structures we use. These interacting photons can undergo Bose-Einstein condensation, which is a state of matter with spontaneous coherence. We can see superfluid flow of the polariton condensate over millimeter distances; we can also trap the condensate in various potentials; and we can see interference due to the coherence of the condensate.

This work connects to several fundamental questions. One topic is how coherence can occur spontaneously ("enphasing") in systems like lasers and condensates and how coherence is lost ("dephasing") in standard quantum systems.  This, in turn, relates to the deep question of why there is irreversibility in nature, that is, the arrow of time. Another topic is how phase transitions can occur in nonequilibrium systems. We have developed sophisticated numerical methods to compare to our data on the momentum distribution and coherence of polariton gases.

We are also looking at novel semiconductor materials that may lead to a new type of superconductivity. This would be a "light-induced superconductor," in which the system is only superconducting under illumination by light. We are also looking at new material systems so that the polariton condensate effects can be moved to room temperature.

Awards

  • APS Outstanding Referee Award, 2016
  • Fellow of the American Physical Society, 2006

Selected Publications

  • D.W. Snoke, “Mathematical formalism for nonlocal spontaneous collapse in quantum field theory,” Foundations of Physics 53, 34 (2023). 
  • Q. Yao, et al., “Ballistic transport of a polariton ring condensate with spin precession,” Physical Review B 106, 245309 (2022). 
  • E. Estrecho, et al., “Low-energy collective oscillations and Bogoliubov sound in an exciton-polariton condensate,” Physical Review Letters 126, 075301 (2021). (editor’s suggestion) 
  • S. Mukherjee, et al., “Dynamics of spin polarization in tilted polariton rings,” Physical Review B 103, 165306 (2021). 
  • Z. Sun, et al., “Charged bosons made of fermions in bilayer structures with strong metallic screening,” Nano Letters 21, 7669 (2021). 
  • D.M. Myers, S. Mukherjee, J. Beaumariage, D. W. Snoke, M. Steger, L. N. Pfeiffer and K. West, “Polariton- enhanced exciton transport,” Physical Review B 98, 235302 (2018). 
  • "The new era of polariton condensates," D.W. Snoke and J. Keeling, Physics Today 70, 54 (October 2017). (feature article)
  • "Bose-Einstein condensation of long-lifetime polaritons in thermal equilibrium,''  Y. Sun, et al., Physical Review Letters 118, 016602 (2017). (highlighted by Viewpoint)
  • "Slow reflection and two-photon generation of microcavity exciton-polaritons," ​Mark Steger, Chitra Gautham, David W. Snoke, Loren Pfeiffer, and Ken West, Optica 2, 1 (2015). (featured in Funsize Physics)
  • "A new type of half-quantum circulation in a macroscopic polariton spinor ring condensate," Gangqiang Liu, David W. Snoke, Andrew Daley, Loren Pfeiffer, and Kenneth West, Proceedings of the National Academy of Sciences (USA) 112, 2676 (2015).
  • "Enhanced Coherence between Condensates Formed Resonantly at Different Times," A. Hayat et al., Optics Express 22, 30559 (2014).
  • "Dissipationless Flow and Sharp Threshold of a Polariton Condensate with Long Lifetime," Bryan Nelsen, et al.,  Physical Review X 3, 041015 (2013).
  • "Dynamic Stark effect in strongly coupled microcavity exciton-polaritons," Alex Hayat et al., Physical Review Letters 109, 033605 (2012).
  • "The Basis of the Second Law of Thermodynamics in Quantum Field Theory," D.W. Snoke, Gangqiang Liu, and S.M. Girvin, Annals of Physics 327, 1825 (2012). 
  • "The Quantum Boltzmann Equation in Semiconductor Physics," D.W. Snoke,  Annalen der Physik 523, 87 (2011).
  • "Polariton Condensates," (feature article) David Snoke and Peter Littlewood, Physics Today 63, 42 (August, 2010).
  • "Bose-Einstein Condensation of Microcavity Polaritons in a Trap," R. Balili, V. Hartwell, D.W. Snoke, L. Pfeiffer and K. West, Science 316, 1007 (2007).

Books

D.W. Snoke, Interpreting Quantum Mechanics: Modern Foundations, (Cambridge University Press, 2024), in press.

D.W. Snoke, Solid State Physics: Essential Concepts, 2nd edition (Cambridge University Press, 2020).

Universal Themes of Bose-Einstein Condensation, N. Proukakis, D.W. Snoke and P.B. Littlewood, eds., (Cambridge University Press, 2017).

D.W. Snoke, Electronics: A Physical Approach, (Pearson, 2015).

S.A. Moskalenko and D.W. Snoke, Bose-Einstein Condensation of Excitons and Biexcitons and Coherent Nonlinear Optics with Excitons, (Cambridge University Press, 2000).

Bose-Einstein Condensation, A. Griffin, D.W. Snoke and S. Stringari, eds., (Cambridge University Press, 1995; paperback, 1996).

Graduate Advisor

Jonathan Beaumariage
Qi Yao
Hassan Alnatah
Qiaochu Wan
Daniel Vaz