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Charles Tahan selected to receive the Presidential Early Career Award for Scientists and Engineers (PECASE)

December 23rd, 2013  |  by  |  published in Blog, News

President Obama today named 102 researchers as recipients of the Presidential Early Career Awards for Scientists and Engineers, the highest honor bestowed by the United States Government on science and engineering professionals in the early stages of their independent research careers.

Preprint: Bottom-up superconducting and Josephson junction devices inside a Group-IV semiconductor

September 2nd, 2013  |  by  |  published in All, News, Preprints

Preprint: Bottom-up superconducting and Josephson junction devices inside a Group-IV semiconductor

We propose superconducting devices made from precision hole-doped regions within a silicon (or germanium) single crystal. We analyze the properties of this superconducting semiconductor and show that practical superconducting wires, Josephson tunnel junctions or weak links, SQUIDs, and qubits are realizable. This work motivates the pursuit of bottom-up superconductivity for improved or fundamentally different technology and physics.

Phys. Rev. B: On-chip cavity quantum phonodynamics with an acceptor qubit in silicon

August 30th, 2013  |  by  |  published in All, Nanotechnology, News, Papers, Phonitons, Quantum Computing

Phys. Rev. B: On-chip cavity quantum phonodynamics with an acceptor qubit in silicon

We describe a chip-based, solid-state analog of cavity-QED utilizing acoustic phonons instead of photons. We show how long-lived and tunable acceptor impurity states in silicon nanomechanical cavities can play the role of a matter nonlinearity for coherent phonons just as, e.g., the Josephson qubit plays in circuit QED. Both strong coupling (number of Rabi oscillations ≲100) and strong dispersive coupling (0.1–2 MHz) regimes can be reached in cavities in the 1–20-GHz range, enabling the control of single phonons, phonon-phonon interactions, dispersive phonon readout of the acceptor qubit, and compatibility with other optomechanical components such as phonon-photon translators. We predict explicit experimental signatures of the acceptor-cavity system.

Preprint: Observation of Autler-Townes effect in a dispersively dressed Jaynes-Cummings system

August 9th, 2013  |  by  |  published in All, News, Preprints, Quantum Computing

Preprint: Observation of Autler-Townes effect in a dispersively dressed Jaynes-Cummings system

Two-tone spectroscopy of a superconducting transmon qubit in a cavity. We find evidence of strongly-coupled atomic physics in these man-made systems.

Superconducting qubits and circuits are a promising technology for a variety of applications, from exploration of physics to quantum information processing or particle detectors.

Nature Communications: Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting

June 27th, 2013  |  by  |  published in All, News, Papers

Nature Communications: Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting

New theory for spin-valley anticrossing and spin-relaxation in realistic silicon quantum dots.

Silicon quantum dots are promising for quantum computing as they offer low memory errors, fast operation, and a hoped-for compatibility with standard semiconductor processes.

March Meeting 2013: Invited talk on cavity quantum phonodynamics, talks on spin-valley relaxation and many-body phononic systems.

March 21st, 2013  |  by  |  published in All, News, Talks

March Meeting 2013: Invited talk on cavity quantum phonodynamics, talks on spin-valley relaxation and many-body phononic systems.

This year’s APS March Meeting in Baltimore was unquestionably a good one. It seemed like everyone showed up. We were happy to be able to give an invited talk on cavity quantum phonodynamics and two theory talks on our work on quantum dot spin-valley relaxation with the Australians and on the theory of proposed many-body phononic systems. Also of note were the two sessions on Quantum Characterization, Verification, and Validation (I, II) and the four(!) on nano/optomechanics (I, II, III, IV).

Preprint: Toward engineered quantum many-body phonon systems

February 26th, 2013  |  by  |  published in All, News, Preprints

Preprint: Toward engineered quantum many-body phonon systems

Arrays of coupled cavity quantum phonodynamical systems in silicon are considered. We study physical systems that can exhibit, e.g., Mott insulator states of phonons due to a strong phonon-phonon interaction (which is mediated by the impurity-cavity-phonon coupling). Our results indicate that quantum many-body phonon systems are achievable both in on-chip nanomechanical systems in silicon and […]

Preprint: Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting

February 6th, 2013  |  by  |  published in All, News, Preprints

Preprint: Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting

Whilst silicon is a promising material for quantum computation, the degeneracy of the conduction band minima (valleys) must be lifted with a splitting sufficient to ensure formation of well-defined and long-lived spin qubits. Here we demonstrate that valley separation can be accurately tuned via electrostatic gate control in a metal-oxide-semiconductor quantum dot, providing splittings spanning […]

Preprint: On-chip quantum phonodynamics

September 20th, 2012  |  by  |  published in All, News, Preprints

Preprint: On-chip quantum phonodynamics

Sound can be just as quantum as light. But our toolbox for single quanta of sound, i.e. phonons, is currently insufficient. Here we describe a new component that enables a chip-based, solid-state analogue of cavity-QED utilizing acoustic phonons instead of photons, phonitons instead of polaritons. We show how long-lived and tunable acceptor (hole) impurity states […]

Phoniton named UMD Invention of the Year Finalist

April 17th, 2012  |  by  |  published in All, News, Phonitons

Could the Next World-Changing Technology Emerge From UMD? (Not exactly how we would hype it, but we appreciate the support!) Phonitons as a Sound-based Analogue of Cavity Quantum Electrodynamics Charles George Tahan, Rousko Todorov Hristov, Oney O. Soykal Researchers at the University of Maryland and the National Security Agency (NSA) have developed the analog of […]

Tahan Research

http://research.tahan.com/

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