TY - JOUR
AB - Observations of flowing granular matter have suggested that same-material tribocharging depends on particle size, typically rendering large grains positive and small ones negative. Models assuming the transfer of trapped electrons can account for this trend, but have not been validated. Tracking individual grains in an electric field, we show quantitatively that charge is transferred based on size between materially identical grains. However, the surface density of trapped electrons, measured independently by thermoluminescence techniques, is orders of magnitude too small to account for the scale of charge transferred. This reveals that trapped electrons are not a necessary ingredient for same-material tribocharging.
AU - Waitukaitis, Scott R
AU - Lee, Victor
AU - Pierson, James
AU - Forman, Steven
AU - Jaeger, Heinrich
ID - 119
IS - 21
JF - APS Physics, Physical Review Letters
TI - Size-dependent same-material tribocharging in insulating grains
VL - 112
ER -
TY - JOUR
AB - Self-propelled particles can exhibit surprising non-equilibrium behaviors, and how they interact with obstacles or boundaries remains an important open problem. Here we show that chemically propelled micro-rods can be captured, with little change in their speed, into close orbits around solid spheres resting on or near a horizontal plane. We show that this interaction between sphere and particle is short-range, occurring even for spheres smaller than the particle length, and for a variety of sphere materials. We consider a simple model, based on lubrication theory, of a force- and torque-free swimmer driven by a surface slip (the phoretic propulsion mechanism) and moving near a solid surface. The model demonstrates capture, or movement towards the surface, and yields speeds independent of distance. This study reveals the crucial aspects of activity–driven interactions of self-propelled particles with passive objects, and brings into question the use of colloidal tracers as probes of active matter.
AU - Takagi, Daisuke
AU - Palacci, Jérémie A
AU - Braunschweig, Adam B.
AU - Shelley, Michael J.
AU - Zhang, Jun
ID - 9050
IS - 11
JF - Soft Matter
KW - General Chemistry
KW - Condensed Matter Physics
SN - 1744-683X
TI - Hydrodynamic capture of microswimmers into sphere-bound orbits
VL - 10
ER -
TY - JOUR
AB - Multielectron spin qubits are demonstrated, and performance examined by comparing coherent exchange oscillations in coupled single-electron and multielectron quantum dots, measured in the same device. Fast (>1 GHz) exchange oscillations with a quality factor Q∼15 are found for the multielectron case, compared to Q∼2 for the single-electron case, the latter consistent with experiments in the literature. A model of dephasing that includes voltage and hyperfine noise is developed that is in good agreement with both single- and multielectron data, though in both cases additional exchange-independent dephasing is needed to obtain quantitative agreement across a broad parameter range.
AU - Higginbotham, Andrew P
AU - Kuemmeth, Ferdinand
AU - Hanson, Micah
AU - Gossard, Arthur
AU - Marcus, Charles
ID - 96
IS - 2
JF - APS Physics, Physical Review Letters
TI - Coherent operations and screening in multielectron spin qubits
VL - 112
ER -
TY - JOUR
AB - The distribution of Coulomb blockade peak heights as a function of magnetic field is investigated experimentally in a Ge-Si nanowire quantum dot. Strong spin-orbit coupling in this hole-gas system leads to antilocalization of Coulomb blockade peaks, consistent with theory. In particular, the peak height distribution has its maximum away from zero at zero magnetic field, with an average that decreases with increasing field. Magnetoconductance in the open-wire regime places a bound on the spin-orbit length (lso < 20 nm), consistent with values extracted in the Coulomb blockade regime (lso < 25 nm).
AU - Higginbotham, Andrew P
AU - Kuemmeth, Ferdinand
AU - Larsen, Thorvald
AU - Fitzpatrick, Mattias
AU - Yao, Jun
AU - Yan, Hao
AU - Lieber, Charles
AU - Marcus, Charles
ID - 97
IS - 21
JF - APS Physics, Physical Review Letters
TI - Antilocalization of coulomb blockade in a Ge/Si nanowire
VL - 112
ER -
TY - JOUR
AB - We propose a method for detecting many-body localization (MBL) in disordered spin systems. The method involves pulsed coherent spin manipulations that probe the dephasing of a given spin due to its entanglement with a set of distant spins. It allows one to distinguish the MBL phase from a noninteracting localized phase and a delocalized phase. In particular, we show that for a properly chosen pulse sequence the MBL phase exhibits a characteristic power-law decay reflecting its slow growth of entanglement. We find that this power-law decay is robust with respect to thermal and disorder averaging, provide numerical simulations supporting our results, and discuss possible experimental realizations in solid-state and cold-atom systems.
AU - Maksym Serbyn
AU - Knap, Michael J
AU - Gopalakrishnan, Sarang
AU - Papić, Zlatko
AU - Yao, Norman Y
AU - Laumann, Chris R
AU - Abanin, Dmitry A
AU - Lukin, Mikhail D
AU - Demler, Eugene A
ID - 977
IS - 14
JF - Physical Review Letters
TI - Interferometric probes of many-body localization
VL - 113
ER -
TY - JOUR
AB - The newly discovered topological crystalline insulators feature a complex band structure involving multiple Dirac cones, and are potentially highly tunable by external electric field, temperature or strain. Theoretically, it has been predicted that the various Dirac cones, which are offset in energy and momentum, might harbour vastly different orbital character. However, their orbital texture, which is of immense importance in determining a variety of a materialâ €™ s properties remains elusive. Here, we unveil the orbital texture of Pb 1â ̂'x Sn x Se, a prototypical topological crystalline insulator. By using Fourier-transform scanning tunnelling spectroscopy we measure the interference patterns produced by the scattering of surface-state electrons. We discover that the intensity and energy dependences of the Fourier transforms show distinct characteristics, which can be directly attributed to orbital effects. Our experiments reveal a complex band topology involving two Lifshitz transitions and establish the orbital nature of the Dirac bands, which could provide an alternative pathway towards future quantum applications.
AU - Zeljkovic, Ilija
AU - Okada, Yoshinori
AU - Huang, Chengyi
AU - Sankar, Raman
AU - Walkup, Daniel
AU - Zhou, Wenwen
AU - Maksym Serbyn
AU - Chou, Fangcheng
AU - Tsai, Wei-Feng
AU - Lin, Hsin
AU - Bansil, Arun
AU - Fu, Liang
AU - Hasan, Md Z
AU - Madhavan, Vidya
ID - 978
IS - 8
JF - Nature Physics
TI - Mapping the unconventional orbital texture in topological crystalline insulators
VL - 10
ER -
TY - JOUR
AB - In the recently discovered topological crystalline insulators SnTe and Pb1-xSnx(Te, Se), crystal symmetry and electronic topology intertwine to create topological surface states with many interesting features including Lifshitz transition, Van-Hove singularity, and fermion mass generation. These surface states are protected by mirror symmetry with respect to the (110) plane. In this work we present a comprehensive study of the effects of different mirror-symmetry-breaking perturbations on the (001) surface band structure. Pristine (001) surface states have four branches of Dirac fermions at low energy. We show that ferroelectric-type structural distortion generates a mass and gaps out some or all of these Dirac points, while strain shifts Dirac points in the Brillouin zone. An in-plane magnetic field leaves the surface state gapless, but introduces asymmetry between Dirac points. Finally, an out-of-plane magnetic field leads to discrete Landau levels. We show that the Landau level spectrum has an unusual pattern of degeneracy and interesting features due to the unique underlying band structure. This suggests that Landau level spectroscopy can detect and distinguish between different mechanisms of symmetry breaking in topological crystalline insulators.
AU - Maksym Serbyn
AU - Fu, Liang
ID - 979
IS - 3
JF - Physical Review B - Condensed Matter and Materials Physics
TI - Symmetry breaking and Landau quantization in topological crystalline insulators
VL - 90
ER -
TY - JOUR
AB - Relaxation and dephasing of hole spins are measured in a gate-defined Ge/Si nanowire double quantum dot using a fast pulsed-gate method and dispersive readout. An inhomogeneous dephasing time T2* ∼ 0.18 μs exceeds corresponding measurements in III-V semiconductors by more than an order of magnitude, as expected for predominately nuclear-spin-free materials. Dephasing is observed to be exponential in time, indicating the presence of a broadband noise source, rather than Gaussian, previously seen in systems with nuclear-spin-dominated dephasing.
AU - Higginbotham, Andrew P
AU - Larsen, Thorvald
AU - Yao, Jun
AU - Yan, Hao
AU - Lieber, Charles
AU - Marcus, Charles
AU - Kuemmeth, Ferdinand
ID - 98
IS - 6
JF - Nano Letters
TI - Hole spin coherence in a Ge/Si heterostructure nanowire
VL - 14
ER -
TY - JOUR
AB - Many-body localized (MBL) systems are characterized by the absence of transport and thermalization and, therefore, cannot be described by conventional statistical mechanics. In this paper, using analytic arguments and numerical simulations, we study the behavior of local observables in an isolated MBL system following a quantum quench. For the case of a global quench, we find that the local observables reach stationary, highly nonthermal values at long times as a result of slow dephasing characteristic of the MBL phase. These stationary values retain the local memory of the initial state due to the existence of local integrals of motion in the MBL phase. The temporal fluctuations around stationary values exhibit universal power-law decay in time, with an exponent set by the localization length and the diagonal entropy of the initial state. Such a power-law decay holds for any local observable and is related to the logarithmic in time growth of entanglement in the MBL phase. This behavior distinguishes the MBL phase from both the Anderson insulator (where no stationary state is reached) and from the ergodic phase (where relaxation is expected to be exponential). For the case of a local quench, we also find a power-law approach of local observables to their stationary values when the system is prepared in a mixed state. Quench protocols considered in this paper can be naturally implemented in systems of ultracold atoms in disordered optical lattices, and the behavior of local observables provides a direct experimental signature of many-body localization.
AU - Maksym Serbyn
AU - Papić, Zlatko
AU - Abanin, Dmitry A
ID - 980
IS - 17
JF - Physical Review B - Condensed Matter and Materials Physics
TI - Quantum quenches in the many-body localized phase
VL - 90
ER -
TY - JOUR
AB - We introduce algorithms for the computation of homology, cohomology, and related operations on cubical cell complexes, using the technique based on a chain contraction from the original chain complex to a reduced one that represents its homology. This work is based on previous results for simplicial complexes, and uses Serre’s diagonalization for cubical cells. An implementation in C++ of the introduced algorithms is available at http://www.pawelpilarczyk.com/chaincon/ together with some examples. The paper is self-contained as much as possible, and is written at a very elementary level, so that basic knowledge of algebraic topology should be sufficient to follow it.
AU - Pawel Pilarczyk
AU - Real, Pedro
ID - 451
IS - 1
JF - Advances in Computational Mathematics
TI - Computation of cubical homology, cohomology, and (co)homological operations via chain contraction
VL - 41
ER -