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Articles 1 - 10 of 10
Full-Text Articles in Quantum Physics
Weakness Of Weak Values: Incompatibility Of Anomalous Pulse-Spectrum Amplification And Optical Frequency Combs, John C. Howell
Weakness Of Weak Values: Incompatibility Of Anomalous Pulse-Spectrum Amplification And Optical Frequency Combs, John C. Howell
Mathematics, Physics, and Computer Science Faculty Articles and Research
We probe the use of optical frequency combs to place lower bounds on anomalous amplification of a weak-value-measured pulse delay, potentially reaching a theoretical temporal resolution of better than 10−34 s. Owing to the interferometric behavior of weak values, we show that anomalous weak value amplification of a time delay is not equivalent to a temporal linear phase ramp. We show that the anomalous weak value is a rearrangement of amplitudes that generates an apparent shift that can be measured in direct detection, but does not change the actual frequency offset of a spectral distribution measurable in coherent detection. …
Roadmap On Superoscillations, Michael Berry, Nicolay Zheludev, Yakir Aharonov, Fabrizio Colombo, Irene Sabadini, Daniele C. Struppa, Jeff Tollaksen, Edward T. F. Rogers, Fei Qin, Minghui Hong, Xiangang Luo, Roei Remez, Ady Arie, Jörg B. Götte, Mark R. Dennis, Alex M. H. Wong, George V. Eleftheriades, Yaniv Eliezer, Alon Bahabad, Gang Chen, Zhongquan Wen, Gaofeng Liang, Chenglong Hao, C-W Qiu, Achim Kempf, Eytan Katzav, Moshe Schwartz
Roadmap On Superoscillations, Michael Berry, Nicolay Zheludev, Yakir Aharonov, Fabrizio Colombo, Irene Sabadini, Daniele C. Struppa, Jeff Tollaksen, Edward T. F. Rogers, Fei Qin, Minghui Hong, Xiangang Luo, Roei Remez, Ady Arie, Jörg B. Götte, Mark R. Dennis, Alex M. H. Wong, George V. Eleftheriades, Yaniv Eliezer, Alon Bahabad, Gang Chen, Zhongquan Wen, Gaofeng Liang, Chenglong Hao, C-W Qiu, Achim Kempf, Eytan Katzav, Moshe Schwartz
Mathematics, Physics, and Computer Science Faculty Articles and Research
Superoscillations are band-limited functions with the counterintuitive property that they can vary arbitrarily faster than their fastest Fourier component, over arbitrarily long intervals. Modern studies originated in quantum theory, but there were anticipations in radar and optics. The mathematical understanding—still being explored—recognises that functions are extremely small where they superoscillate; this has implications for information theory. Applications to optical vortices, sub-wavelength microscopy and related areas of nanoscience are now moving from the theoretical and the demonstrative to the practical. This Roadmap surveys all these areas, providing background, current research, and anticipating future developments.
Completely Top–Down Hierarchical Structure In Quantum Mechanics, Yakir Aharonov, Eliahu Cohen, Jeff Tollaksen
Completely Top–Down Hierarchical Structure In Quantum Mechanics, Yakir Aharonov, Eliahu Cohen, Jeff Tollaksen
Mathematics, Physics, and Computer Science Faculty Articles and Research
Can a large system be fully characterized using its subsystems via inductive reasoning? Is it possible to completely reduce the behavior of a complex system to the behavior of its simplest “atoms”? In this paper we answer these questions in the negative for a specific class of systems and measurements. After a general introduction of the topic, we present the main idea with a simple two-particle example, where strong correlations arise between two apparently empty boxes. This leads to surprising effects within atomic and electromagnetic systems. A general construction based on preand postselected ensembles is then suggested, wherein the Nbody …
Quasiprobability Behind The Out-Of-Time-Ordered Correlator, Nicole Yunger Halpern, Brian Swingle, Justin Dressel
Quasiprobability Behind The Out-Of-Time-Ordered Correlator, Nicole Yunger Halpern, Brian Swingle, Justin Dressel
Mathematics, Physics, and Computer Science Faculty Articles and Research
Two topics, evolving rapidly in separate fields, were combined recently: the out-of-time-ordered correlator (OTOC) signals quantum-information scrambling in many-body systems. The Kirkwood-Dirac (KD) quasiprobability represents operators in quantum optics. The OTOC was shown to equal a moment of a summed quasiprobability [Yunger Halpern, Phys. Rev. A 95, 012120 (2017)]. That quasiprobability, we argue, is an extension of the KD distribution. We explore the quasiprobability's structure from experimental, numerical, and theoretical perspectives. First, we simplify and analyze Yunger Halpern's weak-measurement and interference protocols for measuring the OTOC and its quasiprobability. We decrease, exponentially in system size, the number of trials …
Linear Feedback Stabilization For A Continuously Monitored Qubit, Taylor Lee Patti, A. Chantasri, Justin Dressel, A. N. Jordan
Linear Feedback Stabilization For A Continuously Monitored Qubit, Taylor Lee Patti, A. Chantasri, Justin Dressel, A. N. Jordan
Student Scholar Symposium Abstracts and Posters
In quantum mechanics, standard or strong measurement approaches generally result in the collapse of an ensemble of wavefunctions into a stochastic mixture of eigenstates. On the other hand, continuous or weak measurements have the propensity to dynamically control the evolution of quantum states over time, guiding the trajectory of the state into non-trivial superpositions and maintaining state purity. This kind of measurement-induced state steering is of great theoretical and experimental interest for the harnessing of quantum bits or "qubits", which are the fundamental unit of the emerging quantum computer. We explore continuous measurement-based quantum state stabilization through linear feedback control …
Weak Values Obtained In Matter-Wave Interferometry, Stephan Sponar, Tobias Denkmayr, Hermann Geppert, Hartmutt Lemmel, Alexandre Matzkin, Jeff Tollaksen, Yuji Hasegawa
Weak Values Obtained In Matter-Wave Interferometry, Stephan Sponar, Tobias Denkmayr, Hermann Geppert, Hartmutt Lemmel, Alexandre Matzkin, Jeff Tollaksen, Yuji Hasegawa
Mathematics, Physics, and Computer Science Faculty Articles and Research
Weak values, introduced more than 25 years ago, underwent a metamorphosis from a theoretical curiosity to a powerful resource in photonics for exploring foundations of quantum mechanics, as well as a practical laboratory tool. Due to the tiny coherence volume of particles used in matter-wave optics, a straightforward implementation of weak measurements is not feasible. We have overcome this hurdle by developing a method to weakly measure a massive particle's spin component. A neutron optical approach is realized by utilizing neutron interferometry, where the neutron's spin is coupled weakly to its spatial degree of freedom. Here, we present how one …
Conservation Of The Spin And Orbital Angular Momenta In Electromagnetism, Konstantin Y. Bliokh, Justin Dressel, Franco Nori
Conservation Of The Spin And Orbital Angular Momenta In Electromagnetism, Konstantin Y. Bliokh, Justin Dressel, Franco Nori
Mathematics, Physics, and Computer Science Faculty Articles and Research
We review and re-examine the description and separation of the spin and orbital angular momenta (AM) of an electromagnetic field in free space. While the spin and orbital AM of light are not separately meaningful physical quantities in orthodox quantum mechanics or classical field theory, these quantities are routinely measured and used for applications in optics. A meaningful quantum description of the spin and orbital AM of light was recently provided by several authors, which describes separately conserved and measurable integral values of these quantities. However, the electromagnetic field theory still lacks corresponding locally conserved spin and orbital AM currents. …
The Classical Limit Of Quantum Optics: Not What It Seems At First Sight, Yakir Aharonov, Alonso Botero, Shmuel Nussinov, Sandu Popescu, Jeff Tollaksen, Lev Vaidman
The Classical Limit Of Quantum Optics: Not What It Seems At First Sight, Yakir Aharonov, Alonso Botero, Shmuel Nussinov, Sandu Popescu, Jeff Tollaksen, Lev Vaidman
Mathematics, Physics, and Computer Science Faculty Articles and Research
What light is and how to describe it has always been a central subject in physics. As our understanding has increased, so have our theories changed: geometrical optics, wave optics and quantum optics are increasingly sophisticated descriptions, each referring to a larger class of phenomena than its predecessor. But how exactly are these theories related? How and when wave optics reduces to geometric optics is a rather simple problem. Similarly, how quantum optics reduces to wave optics has also been considered to be a very simple business. It is not so. As we show here the classical limit of quantum …
Quantum Interference Experiments, Modular Variables And Weak Measurements, Jeff Tollaksen, Yakir Aharonov, Aharon Casher, Tirzah Kaufherr, Shmuel Nussinov
Quantum Interference Experiments, Modular Variables And Weak Measurements, Jeff Tollaksen, Yakir Aharonov, Aharon Casher, Tirzah Kaufherr, Shmuel Nussinov
Mathematics, Physics, and Computer Science Faculty Articles and Research
We address the problem of interference using the Heisenberg picture and highlight some new aspects through the use of pre-selection, post-selection, weak measurements and modular variables. We present a physical explanation for the different behaviors of a single particle when the distant slit is open or closed; instead of having a quantum wave that passes through all slits, we have a localized particle with non-local interactions with the other slit(s). We introduce a Gedanken experiment to measure this non-local exchange. While the Heisenberg and Schrodinger pictures are equivalent formulations of quantum mechanics, nevertheless, the results discussed here support a new …
Color Transparency In Qcd And Post-Selection In Quantum Mechanics, Shmuel Nussinov, Jeff Tollaksen
Color Transparency In Qcd And Post-Selection In Quantum Mechanics, Shmuel Nussinov, Jeff Tollaksen
Mathematics, Physics, and Computer Science Faculty Articles and Research
We discuss color transparency in the nuclear QCD context from the perspective of pre- and post-selected ensembles. We show that the small size of the hadronic states can be explained by the peculiar "force of post-selection," in contrast to the more standard explanation based on external forces.