Quantum Information

Quantum mechanics redefines information and its fundamental properties. Researchers at Perimeter Institute work to understand the properties of quantum information and study which information processing tasks are feasible, and which are infeasible or impossible. This includes research in quantum cryptography, which studies the trade-off between information extraction and disturbance, and its applications. It also includes research in quantum error correction, which involves the study of methods for protecting information against decoherence. Another important side of the field is studying the application of quantum information techniques and insights to other areas of physics, including quantum foundations and condensed matter.

Displaying 85 - 96 of 1155

NLTS Hamiltonians from good quantum codes

Anurag Anshu Harvard University
September 28, 2022
PIRSA:22090094
Quantum Information
New Frontiers in Machine Learning and Quantum

10 talks

November 22, 2022 - November 23, 2022

Collection Number C22034
Talk

Quantum adiabatic speedup on a class of combinatorial optimization problems

Madelyn Cain Harvard University

Madelyn Cain

November 22, 2022
PIRSA:22110083

Condensed Matter

Towards an artificial Muse for new ideas in Quantum Physics

Mario Krenn Max Planck Institute for the Science of Light

November 22, 2022
PIRSA:22110085

Condensed Matter

Matchgate Shadows for Fermionic Quantum Simulation

Kianna Wan

Kianna Wan

November 22, 2022
PIRSA:22110086

Condensed Matter

Self-Correcting Quantum Many-Body Control using Reinforcement Learning with Tensor Networks

Friederike Metz IBM (United States)

November 22, 2022
PIRSA:22110087

Condensed Matter

A Study of Neural Network Field Theories

Anindita Maiti Perimeter Institute for Theoretical Physics

November 22, 2022
PIRSA:22110088

Condensed Matter

Quantum hypernetworks

Juan Carrasquilla Vector Institute for Artificial Intelligence

November 22, 2022
PIRSA:22110089

Condensed Matter

Representing quantum states with spiking neural networks

Stefanie Czischek University of Ottawa

Stefanie Czischek

November 23, 2022
PIRSA:22110090

Condensed Matter

Adaptive Quantum State Tomography with Active Learning

Hannah Lange Ludwig-Maximilians-Universitiät München (LMU)

November 23, 2022
PIRSA:22110092

Condensed Matter
See all from this collection
Quantum state control of ultracold chemistry

Alan Jamison Institute for Quantum Computing (IQC)
July 15, 2022
PIRSA:22070023
Quantum Information
Photon-bubble turbulence in cold atomic gases

Hugo Terças Instituto de Plasmas e Fusão Nuclear
July 15, 2022
PIRSA:22070022
Quantum Information
Rydberg atoms in Bose-Einstein condensed environments: cold bubble chambers and mesoscopic entanglement

Sebastian Wüster Indian Institute of Science Education and Research, Bhopal
July 15, 2022
PIRSA:22070021
Quantum Information
Measurements of blackbody-radiation-induced transition rates between high-lying S, P, and D Rydberg levels

Donatella Ciampini Università di Pisa
July 15, 2022
PIRSA:22070020
Quantum Information
Towards an optogalvanic flux sensor for nitric oxide based on Rydberg excitations

Harald Kübler University of Stuttgart
July 15, 2022
PIRSA:22070019
Quantum Information
Opportunities and Limitations for Warm Rydberg Electric Field Sensors

Paul Kunz United States Army Research Laboratory
July 15, 2022
PIRSA:22070018
Quantum Information
Advances in Sensitivity and Pulse Detection with Rydberg-Atom Electrometry

Stephanie Bohaichuk Quantum Valley Ideas Laboratories
July 15, 2022
PIRSA:22070017
Quantum Information
Coherent Light Shift of Alkaline-Earth Rydberg Atoms

Patrick Cheinet Laboratoire Aimé Cotton, CNRS
July 15, 2022
PIRSA:22070016
Quantum Information
Time-optimal gates for quantum computing with Rydberg atoms

Guido Pupillo University of Strasbourg
July 15, 2022
PIRSA:22070015
Quantum Information
Quantum circuits on neutral atom computers

Mark Saffman University of Wisconsin–Madison
July 15, 2022
PIRSA:22070014
Quantum Information

NLTS Hamiltonians from good quantum codes

Anurag Anshu Harvard University
September 28, 2022
PIRSA:22090094
Quantum Information
The NLTS (No Low-Energy Trivial State) conjecture of Freedman and Hastings [2014] posits that there exist families of Hamiltonians with all low energy states of non-trivial complexity (with complexity measured by the quantum circuit depth preparing the state). Our recent work https://arxiv.org/abs/2206.13228 (with Nikolas Breuckmann and Chinmay Nirkhe) proves this conjecture by showing that the recently discovered families of constant-rate and linear-distance QLDPC codes correspond to NLTS local Hamiltonians. This talk will provide background on the conjecture, its relevance to quantum many-body physics and quantum complexity theory, and touch upon the proof techniques.

Zoom link: https://pitp.zoom.us/j/94224635225?pwd=SUovNXA3MWlkRUJlcTIxV0pLQzQxdz09
New Frontiers in Machine Learning and Quantum

10 talks

November 22, 2022 - November 23, 2022

Collection Number C22034

This workshop will bring together a group of young trendsetters working at the frontier of machine learning and quantum information. The workshop will feature two days of talks, and ample time for participants to interact and form new collaborations in the inspiring environment of the Perimeter Institute. Topics will include machine learning, quantum field theory, quantum information, and unifying theoretical concepts.

https://pirsa.org/C22034

Territorial Land Acknowledgement

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land.

We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.
Talk

Quantum adiabatic speedup on a class of combinatorial optimization problems

Madelyn Cain Harvard University

Madelyn Cain

November 22, 2022
PIRSA:22110083

Condensed Matter

Towards an artificial Muse for new ideas in Quantum Physics

Mario Krenn Max Planck Institute for the Science of Light

November 22, 2022
PIRSA:22110085

Condensed Matter

Matchgate Shadows for Fermionic Quantum Simulation

Kianna Wan

Kianna Wan

November 22, 2022
PIRSA:22110086

Condensed Matter

Self-Correcting Quantum Many-Body Control using Reinforcement Learning with Tensor Networks

Friederike Metz IBM (United States)

November 22, 2022
PIRSA:22110087

Condensed Matter

A Study of Neural Network Field Theories

Anindita Maiti Perimeter Institute for Theoretical Physics

November 22, 2022
PIRSA:22110088

Condensed Matter

Quantum hypernetworks

Juan Carrasquilla Vector Institute for Artificial Intelligence

November 22, 2022
PIRSA:22110089

Condensed Matter

Representing quantum states with spiking neural networks

Stefanie Czischek University of Ottawa

Stefanie Czischek

November 23, 2022
PIRSA:22110090

Condensed Matter

Adaptive Quantum State Tomography with Active Learning

Hannah Lange Ludwig-Maximilians-Universitiät München (LMU)

November 23, 2022
PIRSA:22110092

Condensed Matter
See all from this collection
Quantum state control of ultracold chemistry

Alan Jamison Institute for Quantum Computing (IQC)
July 15, 2022
PIRSA:22070023
Quantum Information
The advent of ultracold molecules opens the possibility to explore chemical reactions with perfect control of the quantum states of the reactants. We report on several surprising results of our work with ultracold NaLi molecules. First, we demonstrate a factor of 100 control of reaction rates between NaLi molecules and Na atoms by changing the atom's spin state. This ability to slow reactions allowed us to demonstrate sympathetic cooling of molecules for the first time. Next, we explore two very different collisional resonances. A resonance in NaLi+Na reactions exemplifies the standard description of chemical resonances. The other, for NaLi+NaLi, is the first ultracold molecule-molecule resonance observed and runs completely counter to the standard description. Simple models relate the complex chemical dynamics to the simple physics of a Fabry-Perot resonantor and point a number of open questions in chemical dynamics that can be explored with ultracold molecules.
Photon-bubble turbulence in cold atomic gases

Hugo Terças Instituto de Plasmas e Fusão Nuclear
July 15, 2022
PIRSA:22070022
Quantum Information
Turbulent radiation flow is ubiquitous in many physical systems where light–matter interaction becomes relevant. Photon bubble instabilities, in particular, have been identified as a possible source of turbulent radiation transport in astrophysical objects such as massive stars and black hole accretion disks. Here, we report on the experimental observation of a photon bubble instability in cold atomic gases, in the presence of multiple scattering of light. A two-fluid theory is developed to model the coupled atom–photon gas and to describe both the saturation of the instability in the regime of quasi-static bubbles and the low-frequency turbulent phase associated with the growth and collapse of photon bubbles inside the atomic sample. We also employ statistical dimensionality reduction techniques to describe the low-dimensional nature of the turbulent regime. The experimental results reported here, along with the theoretical model we have developed, may shed light on analogue photon bubble instabilities in astrophysical scenarios. Our findings are consistent with recent analyses based on spatially resolved pump–probe measurements.
Rydberg atoms in Bose-Einstein condensed environments: cold bubble chambers and mesoscopic entanglement

Sebastian Wüster Indian Institute of Science Education and Research, Bhopal
July 15, 2022
PIRSA:22070021
Quantum Information
"S. Tiwari, S. Rammohan, A. Mishra, A. Pendse, A. K. Chauhan, R. Nath, F. Engel, M. Wagner, R.Schmidt, F. Meinert, A. Eisfeld and S. Wüster Indian Institute of Science Education and Research, Bhopal India Palacký University, Olomouc, Czech Republic Indian Institute of Science Education and Research, Pune, India Max Planck Institute for the Physics of Complex Systems, Dresden, Germany Universität Stuttgart, Germany Max-Planck-Institute of Quantum Optics and MCQST, Garching, Germany Rydberg Atoms in highly excited electronic states with n=30-200 can be excited within BoseEinstein condensates (BECs), and while lifetimes are shorter than in vacuum [1,2], they live long enough to cause a response of the BEC mean field [3]. During this, thousands of ground-state atoms are present within the Rydberg orbit, allowing the study of atoms moving within atoms [4]. We present beyond-mean field models of the joint Rydberg-BEC dynamics, showing how either can be used to probe the other. For multiple Rydberg atoms in a single electronic state, we show that the phase coherence of thecondensate allows the tracking of mobile Rydberg impurities akin to the function of bubblechambers in particle physics [5]. For a single Rydberg atom with multiple electronic states, weprovide spectral densities of the BEC as a decohering environment [6], and show that the BECcan image a signature of the entangling evolution that causes Rydberg q-bit decoherence [7] or serve as non-Markovian environment for quantum simulations. [1] Schlagmüller et al. PRX 6 (2016) 031020. [2] Kanungo et al. PRA 102 (2020) 063317. [3] Balewski et al. Nature 502 (2013) 664. [4] Tiwari et al. arXiv:2111.05031 (2021) [5] Tiwari et al. PRA 99 (2019) 043616. [6] Rammohan et al. PRA 103 (2021) 063307. [7] Rammohan et al. PRA(Letters) 104 (2021) L060202."
Measurements of blackbody-radiation-induced transition rates between high-lying S, P, and D Rydberg levels

Donatella Ciampini Università di Pisa
July 15, 2022
PIRSA:22070020
Quantum Information
We report experimental measurements of the rates of blackbody-radiation-induced transitions between highlying (n > 60) S, P, and D Rydberg levels of rubidium atoms in a magneto-optical trap using a hybrid field ionization and state-selective depumping technique. Our results reveal significant deviations of the measured transition rates from theory for well-defined ranges of the principal quantum number. We assume that the most likely cause for those deviations is a modified blackbody spectrum inside the glass cell in which the magneto-optical trap is formed, and we test this assumption by installing electrodes to create an additional microwave cavity around the cell. From the results, we conclude that it should be possible to use such external cavities to control and suppress the blackbody-radiation-induced transitions."
Towards an optogalvanic flux sensor for nitric oxide based on Rydberg excitations

Harald Kübler University of Stuttgart
July 15, 2022
PIRSA:22070019
Quantum Information
I will talk about the applicability of a new kind of gas sensor based on Rydberg excitations. From a gas mixture the molecule in question is excited to a Rydberg state. By succeeding collisions with all other gas components this molecule ionizes and the emerging electrons can be measured as a current. I will show Doppler-free spectra for the A <- X transition, an estimate of the excitation efficiency dependent on the used laser powers, the applied charge-extraction voltage as well as the overall gas pressure and a first Stark map of NO Rydberg states recorded with cw excitation.
Opportunities and Limitations for Warm Rydberg Electric Field Sensors

Paul Kunz United States Army Research Laboratory
July 15, 2022
PIRSA:22070018
Quantum Information
Electric field sensors based on warm vapors of Rydberg atoms have distinguishing features that offer new application possibilities. A single sensor can operate over a wide spectrum of frequencies, from DC to THz, with a consistent instantaneous baseband bandwidth of approximately 10MHz. The sensor head containing the vapor is highly transparent and can be made small relative to the electric field wavelengths, enabling accurate measurements with sub-wavelength spatial resolution. Presently Rydberg sensors rely on the spectroscopic method of electromagnetically induced transparency (EIT) for preparing and probing the atoms, and though simple and effective, this places limits on the sensitivity and instantaneous bandwidth of the sensor. I will discuss these limitations and the optimal EIT parameter regime considering presently available laser technology, and show performance of a promising new prototype vertical external cavity surface emitting laser (VECSEL). Finally, I will present results on recent demonstrations, such as a Rydberg-based spectrum analyzer with sensitivity of -145dBm/Hz and dynamic range >80 dB.
Advances in Sensitivity and Pulse Detection with Rydberg-Atom Electrometry

Stephanie Bohaichuk Quantum Valley Ideas Laboratories
July 15, 2022
PIRSA:22070017
Quantum Information
The strong interaction of optically excited Rydberg atoms with external fields has made them promising for the detection of radio frequency (RF) electric fields with high sensitivity. Such Rydberg-atom based sensors offer advantages over conventional metal antennas in RF transparency and self-calibration, enabled by all-dielectric construction and extremely well-known atomic properties. In this talk, we describe recent advances in the sensing of low amplitude RF electric fields and the timing of sub-microsecond RF pulses using room temperature Cesium vapour cells. We examine their transient response to RF pulses with durations ranging from 10 μs to 50 ns, identifying the dependence of atomic time scales on Rabi frequencies and dephasing mechanisms. We present a method for extracting the arrival time of RF pulses in a typical two-photon setup using a matched filter tailored to the atomic response, achieving a field sensitivity down to ~240 nV cm-1 Hz-1/2 and a timing precision of ~30 ns. On the other hand, practical operation at room temperature results in the self-calibration and sensitivity of this setup being limited by residual Doppler broadening. We therefore develop a novel sub-Doppler approach using a colinear three-photon scheme, which extends the self-calibrated Autler-Townes regime to significantly weaker RF electric fields. With this setup, we achieve a ~200 kHz spectral linewidth of the Rydberg atoms’ electromagnetically induced transparency within a room temperature vapour cell. The results demonstrate the potential of Rydberg atombased sensors for use in test and measurement, communications, and radar applications. "
Coherent Light Shift of Alkaline-Earth Rydberg Atoms

Patrick Cheinet Laboratoire Aimé Cotton, CNRS
July 15, 2022
PIRSA:22070016
Quantum Information
Time-optimal gates for quantum computing with Rydberg atoms

Guido Pupillo University of Strasbourg
July 15, 2022
PIRSA:22070015
Quantum Information
"Neutral atoms have emerged as a competitive platform for digital quantum simulations and computing. In this talk, we discuss recent results on the design of time-optimal two- and three-qubit gates for neutral atoms, where entangling gates are implemented via the strong and long-range interactions provided by highly excited Rydberg states. We combine numerical and semi-analytical quantum optimal control techniques to obtain theoretically laser pulses that are “smooth”, time-optimal and “global” -- that is, they do not require individual addressability of the atoms. This technique improves upon current implementations of the controlled-Z (CZ) and the three-qubit C2Z gates with just a limited set of variational parameters, demonstrating the potential of quantum optimal control techniques for advancing quantum computing with Rydberg atoms."
Quantum circuits on neutral atom computers

Mark Saffman University of Wisconsin–Madison
July 15, 2022
PIRSA:22070014
Quantum Information
"Neutral atom quantum computers with Rydberg mediated entangling gates are rapidly advancing as a leading platform for quantum information processing. I will present recent results running quantum algorithms for preparation of multi-qubit GHZ states, phase estimation, and hybrid quantum/classical optimization. Future fault tolerant quantum processors will require large numbers of qubits, high fidelity gates, and error correcting protocols. Work in progress towards fault tolerance including preparation of arrays of more than 1000 atoms, mid-circuit measurements, and multi-qubit gates will be presented"

Title	Speaker(s)	Date	Talk Type	Info link
NLTS Hamiltonians from good quantum codes	Anurag Anshu	2022-09-28	Scientific Series	View details
New Frontiers in Machine Learning and Quantum				View details
Quantum state control of ultracold chemistry	Alan Jamison	2022-07-15	Conference	View details
Photon-bubble turbulence in cold atomic gases	Hugo Terças	2022-07-15	Conference	View details
Rydberg atoms in Bose-Einstein condensed environments: cold bubble chambers and mesoscopic entanglement	Sebastian Wüster	2022-07-15	Conference	View details
Measurements of blackbody-radiation-induced transition rates between high-lying S, P, and D Rydberg levels	Donatella Ciampini	2022-07-15	Conference	View details
Towards an optogalvanic flux sensor for nitric oxide based on Rydberg excitations	Harald Kübler	2022-07-15	Conference	View details
Opportunities and Limitations for Warm Rydberg Electric Field Sensors	Paul Kunz	2022-07-15	Conference	View details
Advances in Sensitivity and Pulse Detection with Rydberg-Atom Electrometry	Stephanie Bohaichuk	2022-07-15	Conference	View details
Coherent Light Shift of Alkaline-Earth Rydberg Atoms	Patrick Cheinet	2022-07-15	Conference	View details
Time-optimal gates for quantum computing with Rydberg atoms	Guido Pupillo	2022-07-15	Conference	View details
Quantum circuits on neutral atom computers	Mark Saffman	2022-07-15	Conference	View details

Quantum Information

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