Superradiance-like Electron Transport through a Quantum Dot

We theoretically show that intriguing features of coherent many-body physics can be observed in electron transport through a quantum dot (QD). We first derive a master equation based framework for electron transport in the Coulomb-blockade regime which includes hyperfine (HF) interaction with the nuclear spin ensemble in the QD. This general tool is then used to study the leakage current through a single QD in a transport setting. We find that, for an initially polarized nuclear system, the proposed setup leads to a strong current peak, in close analogy with superradiant emission of photons from atomic ensembles. This effect could be observed with realistic experimental parameters and would provide clear evidence of coherent HF dynamics of nuclear spin ensembles in QDs.Comment: 21 pages, 10 figure

Nuclear Spin Dynamics in Double Quantum Dots: Multi-Stability, Dynamical Polarization, Criticality and Entanglement

We theoretically study the nuclear spin dynamics driven by electron transport and hyperfine interaction in an electrically-defined double quantum dot (DQD) in the Pauli-blockade regime. We derive a master-equation-based framework and show that the coupled electron-nuclear system displays an instability towards the buildup of large nuclear spin polarization gradients in the two quantum dots. In the presence of such inhomogeneous magnetic fields, a quantum interference effect in the collective hyperfine coupling results in sizable nuclear spin entanglement between the two quantum dots in the steady state of the evolution. We investigate this effect using analytical and numerical techniques, and demonstrate its robustness under various types of imperfections.Comment: 35 pages, 19 figures. This article provides the full analysis of a scheme proposed in Phys. Rev. Lett. 111, 246802 (2013). v2: version as publishe

The Jurisdiction of the D.C. Circuit

The U.S. Court of Appeals for the D.C. Circuit is unique among federal courts, well known for an unusual caseload that is disproportionally weighted toward administrative law. What explains that unusual caseload? This Article explores that question. We identify several factors that “push” some types of cases away from the Circuit and several factors that “pull” other cases to it. We give particular focus to the jurisdictional provisions of federal statutes, which reveal congressional intent about the types of actions over which the D.C. Circuit should have special jurisdiction. Through a comprehensive examination of the U.S. Code, we identify several trends. First, the Congress is more likely to give the D.C. Circuit exclusive jurisdiction over the review of administrative rulemaking than over the review of agency decisions imposing a penalty. Second, the Congress is more likely to give the D.C. Circuit exclusive jurisdiction over the review of independent agency actions than over the review of executive agency actions. Finally, the Congress tends to grant the D.C. Circuit exclusive jurisdiction over matters that are likely to have a national effect. In sum, we explore what makes this court unique, from its history to its modern docket and jurisdiction

Light Rare Earth Element Depletion During Deepwater Horizon Blowout Methanotrophy

Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation samples revealed that LREE-containing MDHs were present. Our field and laboratory observations provide further insight into the biochemical pathways of methanotrophy during the DWH blowout. Additionally, our results are the first observations of direct biological alteration of REE distributions in oceanic systems. In view of the ubiquity of LREE-containing MDHs in oceanic systems, our results suggest that biological uptake of LREEs is an overlooked aspect of the oceanic geochemistry of this group of elements previously thought to be biologically inactive and an unresolved factor in the flux of methane, a potent greenhouse gas, from the ocean

The Jurisdiction of the D.C. Circuit

The U.S. Court of Appeals for the D.C. Circuit is unique among federal courts, well known for an unusual caseload that is disproportionally weighted toward administrative law. What explains that unusual caseload? This Article explores that question. We identify several factors that “push” some types of cases away from the Circuit and several factors that “pull” other cases to it. We give particular focus to the jurisdictional provisions of federal statutes, which reveal congressional intent about the types of actions over which the D.C. Circuit should have special jurisdiction. Through a comprehensive examination of the U.S. Code, we identify several trends. First, the Congress is more likely to give the D.C. Circuit exclusive jurisdiction over the review of administrative rulemaking than over the review of agency decisions imposing a penalty. Second, the Congress is more likely to give the D.C. Circuit exclusive jurisdiction over the review of independent agency actions than over the review of executive agency actions. Finally, the Congress tends to grant the D.C. Circuit exclusive jurisdiction over matters that are likely to have a national effect. In sum, we explore what makes this court unique, from its history to its modern docket and jurisdiction

Light Rare Earth Element Depletion During Deepwater Horizon Blowout Methanotrophy

Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation samples revealed that LREE-containing MDHs were present. Our field and laboratory observations provide further insight into the biochemical pathways of methanotrophy during the DWH blowout. Additionally, our results are the first observations of direct biological alteration of REE distributions in oceanic systems. In view of the ubiquity of LREE-containing MDHs in oceanic systems, our results suggest that biological uptake of LREEs is an overlooked aspect of the oceanic geochemistry of this group of elements previously thought to be biologically inactive and an unresolved factor in the flux of methane, a potent greenhouse gas, from the ocean

Heisenberg-Limited Atom Clocks Based on Entangled Qubits

We present a quantum-enhanced atomic clock protocol based on groups of sequentially larger Greenberger-Horne-Zeilinger (GHZ) states that achieves the best clock stability allowed by quantum theory up to a logarithmic correction. Importantly the protocol is designed to work under realistic conditions where the drift of the phase of the laser interrogating the atoms is the main source of decoherence. The simultaneous interrogation of the laser phase with a cascade of GHZ states realizes an incoherent version of the phase estimation algorithm that enables Heisenberg-limited operation while extending the coherent interrogation time beyond the laser noise limit. We compare and merge the new protocol with existing state of the art interrogation schemes, and identify the precise conditions under which entanglement provides an advantage for clock stabilization: it allows a significant gain in the stability for short averaging time.Physic