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Digital quantum magnetism on a trapped-ion quantum computer
Authors:
Reza Haghshenas,
Eli Chertkov,
Michael Mills,
Wilhelm Kadow,
Sheng-Hsuan Lin,
Yi-Hsiang Chen,
Chris Cade,
Ido Niesen,
Tomislav Begušić,
Manuel S. Rudolph,
Cristina Cirstoiu,
Kevin Hemery,
Conor Mc Keever,
Michael Lubasch,
Etienne Granet,
Charles H. Baldwin,
John P. Bartolotta,
Matthew Bohn,
Justin J. Burau,
Julia Cline,
Matthew DeCross,
Joan M. Dreiling,
Cameron Foltz,
David Francois,
John P. Gaebler
, et al. (34 additional authors not shown)
Abstract:
Digital quantum matter -- realized when discrete quantum gates approximate continuous time evolution -- is susceptible to heating into chaotic, structureless states. If digitization errors are adequately suppressed, a long-lived transient regime of approximately energy-conserving dynamics can be observed on gate-based quantum computers. Conservation of energy, in turn, enables the exploration of a…
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Digital quantum matter -- realized when discrete quantum gates approximate continuous time evolution -- is susceptible to heating into chaotic, structureless states. If digitization errors are adequately suppressed, a long-lived transient regime of approximately energy-conserving dynamics can be observed on gate-based quantum computers. Conservation of energy, in turn, enables the exploration of a wide variety of complex behaviors observed in equilibrium systems, ranging from the nontrivial microscopic origins of thermalization itself to the stabilization of effective models hosting exotic emergent properties. Here, we use Quantinuum's system model H2 quantum computer to simulate digitized dynamics of the quantum Ising model, suppressing digitization errors well enough to observe thermalization on timescales that severely challenge classical simulation methods. Relaxation of an inhomogeneous state reveals an emergent hydrodynamics due to approximate energy conservation, and we compute the associated diffusion constant. By reprogramming our simulations to take place on a triangular lattice with periodic boundary conditions, we observe thermalization consistent with emergent gauge and topological constraints resulting from lattice frustration. Our results were enabled by continued advances in two-qubit gate quality (native partial entangler fidelities of $99.94(1)\%$), and establish digital quantum computers as powerful tools for studying (effectively) continuous-time dynamics.
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Submitted 21 April, 2026; v1 submitted 26 March, 2025;
originally announced March 2025.
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Singular Value Decomposition and Entropy Dimension of Fractals
Authors:
Xiaojing Weng,
Altai Perry,
Michael Maroun,
Luat T. Vuong
Abstract:
We analyze the singular value decomposition (SVD) and SVD entropy of Cantor fractals produced by the Kronecker product. Our primary results show that SVD entropy is a measure of image ``complexity dimension" that is invariant under the number of Kronecker-product self-iterations (i.e., fractal order). SVD entropy is therefore similar to the fractal Hausdorff complexity dimension but suitable for c…
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We analyze the singular value decomposition (SVD) and SVD entropy of Cantor fractals produced by the Kronecker product. Our primary results show that SVD entropy is a measure of image ``complexity dimension" that is invariant under the number of Kronecker-product self-iterations (i.e., fractal order). SVD entropy is therefore similar to the fractal Hausdorff complexity dimension but suitable for characterizing fractal wave phenomena. Our field-based normalization (Renyi entropy index = 1) illustrates the uncommon step-shaped and cluster-patterned distributions of the fractal singular values and their SVD entropy. As a modal measure of complexity, SVD entropy has uses for a variety of wireless communication, free-space optical, and remote sensing applications.
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Submitted 15 November, 2022;
originally announced November 2022.
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Multiple-camera defocus imaging of ultracold atomic gases
Authors:
A. R. Perry,
S. Sugawa,
F. Salces-Carcoba,
Y. Yue,
I. B. Spielman
Abstract:
In cold atom experiments, each image of light refracted and absorbed by an atomic ensemble carries a remarkable amount of information. Numerous imaging techniques including absorption, fluorescence, and phase-contrast are commonly used. Other techniques such as off-resonance defocused imaging (ORDI), where an in-focus image is deconvolved from a defocused image, have been demonstrated but find onl…
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In cold atom experiments, each image of light refracted and absorbed by an atomic ensemble carries a remarkable amount of information. Numerous imaging techniques including absorption, fluorescence, and phase-contrast are commonly used. Other techniques such as off-resonance defocused imaging (ORDI), where an in-focus image is deconvolved from a defocused image, have been demonstrated but find only niche applications. The ORDI inversion process introduces systematic artifacts because it relies on regularization to account for missing information at some spatial frequencies. In the present work, we extend ORDI to use multiple cameras simultaneously at degrees of defocus, eliminating the need for regularization and its attendant artifacts. We demonstrate this technique by imaging Bose-Einstein condensates, and show that the statistical uncertainties in the measured column density using the multiple-camera off-resonance defocused (MORD) imaging method are competitive with absorption imaging near resonance and phase contrast imaging far from resonance. Experimentally, the MORD method may be incorporated into existing set-ups with minimal additional equipment.
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Submitted 16 February, 2021;
originally announced February 2021.
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Observation of a non-Abelian Yang Monopole: From New Chern Numbers to a Topological Transition
Authors:
Seiji Sugawa,
Francisco Salces-Carcoba,
Abigail R. Perry,
Yuchen Yue,
Ian B. Spielman
Abstract:
Because global topological properties are robust against local perturbations, understanding and manipulating the topological properties of physical systems is essential in advancing quantum science and technology. For quantum computation, topologically protected qubit operations can increase computational robustness, and for metrology the quantized Hall effect directly defines the von Klitzing con…
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Because global topological properties are robust against local perturbations, understanding and manipulating the topological properties of physical systems is essential in advancing quantum science and technology. For quantum computation, topologically protected qubit operations can increase computational robustness, and for metrology the quantized Hall effect directly defines the von Klitzing constant. Fundamentally, topological order is generated by singularities called topological defects in extended spaces, and is quantified in terms of Chern numbers, each of which measures different sorts of fields traversing surfaces enclosing these topological singularities. Here, inspired by high energy theories, we describe our synthesis and characterization of a singularity present in non-Abelian gauge theories - a Yang monopole - using atomic Bose-Einstein condensates in a five-dimensional space, and quantify the monopole in terms of Chern numbers measured on enclosing manifolds. While the well-known 1st Chern number vanished, the 2nd Chern number, measured for the first time in any physical settings, did not. By displacing the manifold, we then observed a phase transition from "topological" to "trivial" as the monopole left the manifold.
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Submitted 19 October, 2016;
originally announced October 2016.
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The spin Hall effect in a quantum gas
Authors:
M. C. Beeler,
R. A. Williams,
K. Jiménez-García,
L. J. LeBlanc,
A. R. Perry,
I. B. Spielman
Abstract:
Electronic properties like current flow are generally independent of the electron's spin angular momentum, an internal degree of freedom present in quantum particles. The spin Hall effects (SHEs), first proposed 40 years ago, are an unusual class of phenomena where flowing particles experience orthogonally directed spin-dependent Lorentz-like forces, analogous to the conventional Lorentz force for…
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Electronic properties like current flow are generally independent of the electron's spin angular momentum, an internal degree of freedom present in quantum particles. The spin Hall effects (SHEs), first proposed 40 years ago, are an unusual class of phenomena where flowing particles experience orthogonally directed spin-dependent Lorentz-like forces, analogous to the conventional Lorentz force for the Hall effect, but opposite in sign for two spin states. Such spin Hall effects have been observed for electrons flowing in spin-orbit coupled materials such as GaAs or InGaAs and for laser light traversing dielectric junctions. Here we observe the spin Hall effect in a quantum-degenerate Bose gas, and use the resulting spin-dependent Lorentz forces to realize a cold-atom spin transistor. By engineering a spatially inhomogeneous spin-orbit coupling field for our quantum gas, we explicitly introduce and measure the requisite spin-dependent Lorentz forces, in excellent agreement with our calculations. This atomtronic circuit element behaves as a new type of velocity-insensitive adiabatic spin-selector, with potential application in devices such as magnetic or inertial sensors. In addition, such techniques --- for both creating and measuring the SHE --- are clear prerequisites for engineering topological insulators and detecting their associated quantized spin Hall effects in quantum gases. As implemented, our system realized a laser-actuated analog to the Datta-Das spin transistor.
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Submitted 22 February, 2014; v1 submitted 15 June, 2013;
originally announced June 2013.
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Direct observation of zitterbewegung in a Bose-Einstein condensate
Authors:
L. J. LeBlanc,
M. C. Beeler,
K. Jimenez-Garcia,
A. R. Perry,
S. Sugawa,
R. A. Williams,
I. B. Spielman
Abstract:
Zitterbewegung, a force-free trembling motion first predicted for relativistic fermions like electrons, was an unexpected consequence of the Dirac equation's unification of quantum mechanics and special relativity. Though the oscillatory motion's large frequency and small amplitude have precluded its measurement with electrons, zitterbewegung is observable via quantum simulation. We engineered an…
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Zitterbewegung, a force-free trembling motion first predicted for relativistic fermions like electrons, was an unexpected consequence of the Dirac equation's unification of quantum mechanics and special relativity. Though the oscillatory motion's large frequency and small amplitude have precluded its measurement with electrons, zitterbewegung is observable via quantum simulation. We engineered an environment for 87Rb Bose-Einstein condensates where the constituent atoms behaved like relativistic particles subject to the one-dimensional Dirac equation. With direct imaging, we observed the sub-micrometer trembling motion of these clouds, demonstrating the utility of neutral ultracold quantum gases for simulating Dirac particles.
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Submitted 3 July, 2013; v1 submitted 4 March, 2013;
originally announced March 2013.
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The Peierls substitution in an engineered lattice potential
Authors:
K. Jiménez-García,
L. J. LeBlanc,
R. A. Williams,
M. C. Beeler,
A. R. Perry,
I. B. Spielman
Abstract:
Artificial gauge fields open new possibilities to realize quantum many-body systems with ultracold atoms, by engineering Hamiltonians usually associated with electronic systems. In the presence of a periodic potential, artificial gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here, we describe a one-dimensional lattice derived purely from effective Zeeman-shifts resultin…
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Artificial gauge fields open new possibilities to realize quantum many-body systems with ultracold atoms, by engineering Hamiltonians usually associated with electronic systems. In the presence of a periodic potential, artificial gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here, we describe a one-dimensional lattice derived purely from effective Zeeman-shifts resulting from a combination of Raman coupling and radiofrequency magnetic fields. In this lattice, the tunneling matrix element is generally complex. We control both the amplitude and the phase of this tunneling parameter, experimentally realizing the Peierls substitution for ultracold neutral atoms.
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Submitted 31 January, 2012;
originally announced January 2012.
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Observation of a superfluid Hall effect
Authors:
L. J. LeBlanc,
K. Jimenez-Garcia,
R. A. Williams,
M. C. Beeler,
A. R. Perry,
W. D. Phillips,
I. B Spielman
Abstract:
Measurement techniques based upon the Hall effect are invaluable tools in condensed matter physics. When an electric current flows perpendicular to a magnetic field, a Hall voltage develops in the direction transverse to both the current and the field. In semiconductors, this behaviour is routinely used to measure the density and charge of the current carriers (electrons in conduction bands or hol…
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Measurement techniques based upon the Hall effect are invaluable tools in condensed matter physics. When an electric current flows perpendicular to a magnetic field, a Hall voltage develops in the direction transverse to both the current and the field. In semiconductors, this behaviour is routinely used to measure the density and charge of the current carriers (electrons in conduction bands or holes in valence bands) -- internal properties of the system that are not accessible from measurements of the conventional resistance. For strongly interacting electron systems, whose behaviour can be very different from the free electron gas, the Hall effect's sensitivity to internal properties makes it a powerful tool; indeed, the quantum Hall effects are named after the tool by which they are most distinctly measured instead of the physics from which the phenomena originate. Here we report the first observation of a Hall effect in an ultracold gas of neutral atoms, revealed by measuring a Bose-Einstein condensate's transport properties perpendicular to a synthetic magnetic field. Our observations in this vortex-free superfluid are in good agreement with hydrodynamic predictions, demonstrating that the system's global irrotationality influences this superfluid Hall signal.
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Submitted 27 January, 2012;
originally announced January 2012.
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Synthetic partial waves in ultracold atomic collisions
Authors:
R. A. Williams,
L. J. LeBlanc,
K. Jimenez-Garcia,
M. C. Beeler,
A. R. Perry,
W. D. Phillips,
I. B. Spielman
Abstract:
Interactions between particles can be strongly altered by their environment. We demonstrate a technique for modifying interactions between ultracold atoms by dressing the bare atomic states with light, creating an effective interaction of vastly increased range that scatters states of finite relative angular momentum at collision energies where only s-wave scattering would normally be expected. We…
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Interactions between particles can be strongly altered by their environment. We demonstrate a technique for modifying interactions between ultracold atoms by dressing the bare atomic states with light, creating an effective interaction of vastly increased range that scatters states of finite relative angular momentum at collision energies where only s-wave scattering would normally be expected. We collided two optically dressed neutral atomic Bose-Einstein condensates with equal, and opposite, momenta and observed that the usual s-wave distribution of scattered atoms was altered by the appearance of d- and g-wave contributions. This technique is expected to enable quantum simulation of exotic systems, including those predicted to support Majorana fermions.
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Submitted 20 January, 2012;
originally announced January 2012.
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Rapid production of $^{87}$Rb BECs in a combined magnetic and optical potential
Authors:
Y. -J. Lin,
A. R. Perry,
R. L. Compton,
I. B. Spielman,
J. V. Porto
Abstract:
We describe an apparatus for quickly and simply producing $\Rb87$ Bose-Einstein condensates. It is based on a magnetic quadrupole trap and a red detuned optical dipole trap. We collect atoms in a magneto-optical trap (MOT) and then capture the atom in a magnetic quadrupole trap and force rf evaporation. We then transfer the resulting cold, dense cloud into a spatially mode-matched optical dipole…
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We describe an apparatus for quickly and simply producing $\Rb87$ Bose-Einstein condensates. It is based on a magnetic quadrupole trap and a red detuned optical dipole trap. We collect atoms in a magneto-optical trap (MOT) and then capture the atom in a magnetic quadrupole trap and force rf evaporation. We then transfer the resulting cold, dense cloud into a spatially mode-matched optical dipole trap by lowering the quadrupole field gradient to below gravity. This technique combines the efficient capture of atoms from a MOT into a magnetic trap with the rapid evaporation of optical dipole traps; the approach is insensitive to the peak quadrupole gradient and the precise trapping beam waist. Our system reliably produces a condensate with $N\approx2\times10^6$ atoms every $16\second$.
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Submitted 21 April, 2009;
originally announced April 2009.
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A Bose-Einstein Condensate in a Uniform Light-induced Vector Potential
Authors:
Y. -J. Lin,
R. L. Compton,
A. R. Perry,
W. D. Phillips,
J. V. Porto,
I. B. Spielman
Abstract:
We use a two-photon dressing field to create an effective vector gauge potential for Bose-condensed Rb atoms in the F=1 hyperfine ground state. The dressed states in this Raman field are spin and momentum superpositions, and we adiabatically load the atoms into the lowest energy dressed state. The effective Hamiltonian of these neutral atoms is like that of charged particles in a uniform magneti…
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We use a two-photon dressing field to create an effective vector gauge potential for Bose-condensed Rb atoms in the F=1 hyperfine ground state. The dressed states in this Raman field are spin and momentum superpositions, and we adiabatically load the atoms into the lowest energy dressed state. The effective Hamiltonian of these neutral atoms is like that of charged particles in a uniform magnetic vector potential, whose magnitude is set by the strength and detuning of Raman coupling. The spin and momentum decomposition of the dressed states reveals the strength of the effective vector potential, and our measurements agree quantitatively with a simple single-particle model. While the uniform effective vector potential described here corresponds to zero magnetic field, our technique can be extended to non-uniform vector potentials, giving non-zero effective magnetic fields.
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Submitted 17 September, 2008;
originally announced September 2008.
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Modulated optical reflectance measurements on La2/3Sr1/3MnO3 thin films
Authors:
Laurence Mechin,
Stephane Flament,
Andy Perry,
Darryl P. Almond,
Radoslav A. Chakalov
Abstract:
The modulated optical reflectance (MOR) measurement technique was applied to colossal magnetoresistive materials, in particular, La2/3Sr1/3MnO3 (LSMO) thin films. The contactless measurement scheme is prospective for many applications spanning from materials characterization to new devices like reading heads for magnetically recorded media. A contrasted room temperature surface scan of a 100 mic…
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The modulated optical reflectance (MOR) measurement technique was applied to colossal magnetoresistive materials, in particular, La2/3Sr1/3MnO3 (LSMO) thin films. The contactless measurement scheme is prospective for many applications spanning from materials characterization to new devices like reading heads for magnetically recorded media. A contrasted room temperature surface scan of a 100 microns wide 400 microns long bridge patterned into LSMO film provided preliminary information about the film homogeneity. Then the temperature was varied between 240 and 400 K, i.e. through the ferromagnetic to paramagnetic transition. A clear relation between the MOR signal measured as function of the temperature and the relative derivative of the resistivity up to the Curie temperature was observed. This relationship is fundamental for the MOR technique and its mechanism was explored in the particular case of LSMO. Analysis in the framework of the Drude model showed that, within certain conditions, the measured MOR signal changes are correlated to changes in the charge carrier concentration.
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Submitted 18 October, 2005;
originally announced October 2005.