About

Professor Donald Candela's research at the University of Massachusetts Amherst focuses on several areas within physics, including granular matter, quantum fluids and solids at low temperatures and high magnetic fields, and fluids in porous media. His recent work on shearing and flowing granular matter involves simulations demonstrating that a pack of soft grains can retain a detailed memory of its shear history. Earlier experimental studies utilized MRI and PFG-NMR techniques to observe the fluctuating motion of grains in gravity-driven dense granular flows through vertical channels, as well as investigations into grain motion in bubbling gas-fluidized beds and anomalous granular heat flow in vibrofluidized granular gases. In the domain of quantum fluids and solids, Professor Candela has collaborated with Neil Sullivan's group at the University of Florida to measure properties of effectively one-dimensional Fermi fluids formed by confining helium-3 to nanopores. His prior work includes observing magnetic relaxation and phase separation of helium-3 impurities in solid helium-4, and using the NHMFL High B/T facility to study giant viscosity increases and field-induced spin wave relaxation in highly polarized helium-3/helium-4 liquid mixtures. Earlier experiments at UMass involved measuring spin and momentum transport in helium-3 systems both in bulk and within silica aerogel pores. His research on fluids in porous media has employed MRI to image the displacement of non-wetting fluids by wetting fluids in porous media, revealing the formation of compact or fractal fronts depending on flow conditions. Additionally, he has studied local and non-local hydrodynamic dispersion of virtual NMR tracers in fluids flowing through porous media. In teaching, Professor Candela has developed projects for a junior-level quantum course that simulate quantum computers, including the surface code array. His teaching materials also include experiments demonstrating quantized conductance in nanocontacts and an invertible pendulum designed by Bessel for measuring gravitational acceleration, along with handouts on scientific programming in Python.

Research topics

• Physics
• Condensed matter physics
• Quantum mechanics
• Materials science
• Composite material
• Chemistry
• Classical mechanics
• Crystallography
• Statistical physics
• Mechanics

Selected publications

• Complex Memory Formation in Frictional Granular Media

  Physical Review Letters · 2023 · 11 citations

  1st authorCorresponding
  • Mechanics
  • Statistical physics
  • Physics

  Using numerical simulations it is shown that a jammed, random pack of soft frictional grains can store an arbitrary waveform that is applied as a small time-dependent shear while the system is slowly compressed. When the system is decompressed at a later time, an approximation of the input waveform is recalled in time-reversed order as shear stresses on the system boundaries. This effect depends on friction between the grains, and is independent of some aspects of the friction model. This type of memory could potentially be observable in other types of random media that form internal contacts when compressed.

  PublisherDOI

• Dynamics of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts/><mml:none/><mml:mn>3</mml:mn></mml:mmultiscripts></mml:math> in one dimension in the Luttinger liquid limit

  Physical review. B./Physical review. B · 2022 · 2 citations

  • Physics
  • Condensed matter physics
  • Quantum mechanics

  NMR techniques have been used to investigate the dynamics of highly degenerate $^{3}\mathrm{He}$ confined to the interior of $^{4}\mathrm{He}$ plated nanotubes of MCM-41 (Mobil Composition Matter No. 41). The $^{3}\mathrm{He}$ line density was $0.93\ifmmode\pm\else\textpm\fi{}0.10\phantom{\rule{0.28em}{0ex}}{\mathrm{nm}}^{\ensuremath{-}1}$, corresponding to a Fermi degeneracy temperature of ${T}_{F}\ensuremath{\approx}0.1$ K. Experiments conducted down to 10 mK reveal a linear temperature dependence of the nuclear spin-lattice relaxation for $T&lt;{T}_{F}$, following a peak at $2{T}_{F}$, which are hallmarks of Luttinger liquid physics.

  PublisherDOI

• Low temperature dynamics of quasi-1d 3 He: NMR studies

  Bulletin of the American Physical Society · 2021-03-15

  article
  Publisher

• Dynamics of 3 He in a quasi-1D environment using 4 He-plated MCM-41: NMR Studies

  Bulletin of the American Physical Society · 2020-03-03

  article
  Publisher

• NMR Studies of the Dynamics of 1D $$^3\hbox {He}$$ in $$^4\hbox {He}$$ Plated MCM-41

  Journal of Low Temperature Physics · 2020 · 3 citations

  • Materials science
  • Condensed matter physics
  • Crystallography
  PublisherDOI

• Nuclear Spin Relaxometry of $$^3$$He Atoms Confined in Mesoporous MCM-41

  Journal of Low Temperature Physics · 2019-01-02 · 6 citations

  article
  PublisherDOI

• Probing the dynamics of 3 He adsorbed on MCM-41 with NMR

  Bulletin of the American Physical Society · 2018-03-05

  article
  Publisher

• Phase separation in dilute solutions of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts/><mml:none/><mml:mn>3</mml:mn></mml:mmultiscripts></mml:math>in solid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts/><mml:none/><mml:mn>4</mml:mn></mml:mmultiscripts></mml:math>

  Physical review. B./Physical review. B · 2017-03-20 · 3 citations

  article

  The dynamics of the phase separation of very dilute ${}^{3}$He-${}^{4}$He solid solutions is studied using high-sensitivity low-temperature NMR techniques. This paper compares the results observed at very low concentrations (down to 16 ppm ${}^{3}$He) with previous results up to 2%. The growth of ${}^{3}$He nanodroplets after phase separation is analyzed and shown to follow a one-third power-law dependence at long times as expected for Ostwald ripening. The time scale for the dynamics is governed by the relatively fast quantum diffusion in solid helium, allowing the long-term behavior of the ripening process to be explored by experiments lasting a few days rather than several months, as in the case of metallic alloys.

  PublisherDOI

• Quantum Tunneling of $$^3$$ 3 He in Solid $$^4$$ 4 He: A New Analysis

  Journal of Low Temperature Physics · 2016-06-15 · 1 citations

  article
  PublisherDOI

• Flow Profiles and Fluctuations Measured for Granular Flow in a Vertical Channel

  Bulletin of the American Physical Society · 2015-03-05

  article1st authorCorresponding
  Publisher

Recent grants

• NMR Studies of Rapid Granular Flows

  NSF · $478k · 2004–2007

Frequent coauthors

• Chao Huan

  Zhejiang University

  35 shared

• N. S. Sullivan

  32 shared

• R. W. Mair

  Harvard University

  28 shared

• Ronald L. Walsworth

  University of Maryland, College Park

  25 shared

• Hikota Akimoto

  RIKEN

  21 shared

• J. S. Xia

  Shandong University of Science and Technology

  18 shared

• Matthew S. Rosen

  Harvard University

  15 shared

• Lan Yin

  Xi'an University of Science and Technology

  12 shared