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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
General Transfer-Function Approach To Noise Filtering In Open-Loop Quantum Control, Gerardo A. Paz-Silva, Lorenza Viola
General Transfer-Function Approach To Noise Filtering In Open-Loop Quantum Control, Gerardo A. Paz-Silva, Lorenza Viola
Dartmouth Scholarship
We present a general transfer-function approach to noise filtering in open-loop Hamiltonian engineering protocols for open quantum systems. We show how to identify a computationally tractable set of fundamental filter functions, out of which arbitrary transfer filter functions may be assembled up to arbitrary high order in principle. Besides avoiding the infinite recursive hierarchy of filter functions that arises in general control scenarios, this fundamental filter-functions set suffices to characterize the error suppression capabilities of the control protocol in both the time and frequency domain. We prove that the resulting notion of filtering order reveals conceptually distinct, albeit complementary, …
Robustness Of Composite Pulses To Time-Dependent Control Noise, Chingiz Kabytayev, Todd J. Green, Kaveh Khodjasteh, Michael J. Biercuk, Lorenza Viola, Kenneth R. Brown
Robustness Of Composite Pulses To Time-Dependent Control Noise, Chingiz Kabytayev, Todd J. Green, Kaveh Khodjasteh, Michael J. Biercuk, Lorenza Viola, Kenneth R. Brown
Dartmouth Scholarship
We study the performance of composite pulses in the presence of time-varying control noise on a single qubit. These protocols, originally devised only to correct for static, systematic errors, are shown to be robust to time-dependent non-Markovian noise in the control field up to frequencies as high as ∼10% of the Rabi frequency. Our study combines a generalized filter-function approach with asymptotic dc-limit calculations to give a simple analytic framework for error analysis applied to a number of composite-pulse sequences relevant to nuclear magnetic resonance as well as quantum information experiments. Results include examination of recently introduced concatenated composite pulses …
Quantum Resources For Purification And Cooling: Fundamental Limits And Opportunities, Francesco Ticozzi, Lorenza Viola
Quantum Resources For Purification And Cooling: Fundamental Limits And Opportunities, Francesco Ticozzi, Lorenza Viola
Dartmouth Scholarship
Preparing a quantum system in a pure state is ultimately limited by the nature of the system's evolution in the presence of its environment and by the initial state of the environment itself. We show that, when the system and environment are initially uncorrelated and arbitrary joint unitary dynamics is allowed, the system may be purified up to a certain (possibly arbitrarily small) threshold if and only if its environment, either natural or engineered, contains a “virtual subsystem” which has the same dimension and is in a state with the desired purity. Beside providing a unified understanding of quantum purification …
The Hyperspherical Four-Fermion Problem, Seth Rittenhouse, J Stecher, J D'Incao, Nirav Mehta, Chris Greene
The Hyperspherical Four-Fermion Problem, Seth Rittenhouse, J Stecher, J D'Incao, Nirav Mehta, Chris Greene
Nirav P Mehta
The problem of a few interacting fermions in quantum physics has sparked intense interest, particularly in recent years owing to connections with the behaviour of superconductors, fermionic superfluids and finite nuclei. This review addresses recent developments in the theoretical description of four fermions having finite-range interactions, stressing insights that have emerged from a hyperspherical coordinate perspective. The subject is complicated, so we have included many detailed formulae that will hopefully make these methods accessible to others interested in using them. The universality regime, where the dominant length scale in the problem is the two-body scattering length, is particularly stressed, including …
Exact And Approximate Solutions For The Quantum Minimum-Kullback-Entropy Estimation Problem, Carlo Sparaciari, Stefano Olivares, Francesco Ticozzi, Matteo G. A. Paris
Exact And Approximate Solutions For The Quantum Minimum-Kullback-Entropy Estimation Problem, Carlo Sparaciari, Stefano Olivares, Francesco Ticozzi, Matteo G. A. Paris
Dartmouth Scholarship
The minimum-Kullback-entropy principle (mKE) is a useful tool to estimate quantum states and operations from incomplete data and prior information. In general, the solution of an mKE problem is analytically challenging and an approximate solution has been proposed and employed in different contexts. Recently, the form and a way to compute the exact solution for finite dimensional systems has been found, and a question naturally arises on whether the approximate solution could be an effective substitute for the exact solution, and in which regimes this substitution can be performed. Here, we provide a systematic comparison between the exact and the …
Majorana Flat Bands In S -Wave Gapless Topological Superconductors, Shusa Deng, Gerardo Ortiz, Amrit Poudel, Lorenza Viola
Majorana Flat Bands In S -Wave Gapless Topological Superconductors, Shusa Deng, Gerardo Ortiz, Amrit Poudel, Lorenza Viola
Dartmouth Scholarship
We demonstrate how the nontrivial interplay between spin-orbit coupling and nodeless s-wave superconductivity can drive a fully gapped two-band topological insulator into a time-reversal invariant gapless topological superconductor supporting symmetry-protected Majorana flat bands. We characterize topological phase diagrams by a Z2×Z2 partial Berry-phase invariant, and show that, despite the trivial crystal geometry, no unique bulk-boundary correspondence exists. We trace this behavior to the anisotropic quasiparticle bulk gap closing, linear vs quadratic, and argue that this provides a unifying principle for gapless topological superconductivity. Experimental implications for tunneling conductance measurements are addressed, relevant for lead chalcogenide materials.
Spannungsfeld, Julian Voss-Andreae
Spannungsfeld, Julian Voss-Andreae
The STEAM Journal
My design for a sculptural installation for the University of Minnesota’s new Physics and Nanotechnology Building is inspired by a view of the human body through the lens of quantum physics.
The German title of the installation (literally "tension field") originated in physics but is used in contemporary German almost exclusively in a metaphorical sense, implying a dynamic tension, often between polar opposites, that permeates everything in its vicinity.
Experimental Realization Of Slowly Rotating Modes Of Light, Fangzhao A. An
Experimental Realization Of Slowly Rotating Modes Of Light, Fangzhao A. An
HMC Senior Theses
Beams of light can carry spin and orbital angular momentum. Spin angular momentum describes how the direction of the electric field rotates about the propagation axis, while orbital angular momentum describes the rotation of the field amplitude pattern. These concepts are well understood for monochromatic beams, but previous theoretical studies have constructed polychromatic superpositions where the connection between angular momentum and rotation of the electric field becomes much less clear. These states are superpositions of two states of light carrying opposite signs of angular momentum and slightly detuned frequencies. They rotate at the typically small detuning frequency and thus we …
Mathematical And Physical Aspects Of Complex Symmetric Operators, Stephan Ramon Garcia, Emil Prodan, Mihai Putinar
Mathematical And Physical Aspects Of Complex Symmetric Operators, Stephan Ramon Garcia, Emil Prodan, Mihai Putinar
Pomona Faculty Publications and Research
Recent advances in the theory of complex symmetric operators are presented and related to current studies in non-hermitian quantum mechanics. The main themes of the survey are: the structure of complex symmetric operators, C-selfadjoint extensions of C-symmetric unbounded operators, resolvent estimates, reality of spectrum, bases of C-orthonormal vectors, and conjugate-linear symmetric operators. The main results are complemented by a variety of natural examples arising in field theory, quantum physics, and complex variables.