The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Mark Lundstrom - One of the best experts on this subject based on the ideXlab platform.
-
on Momentum Conservation and thermionic emission cooling
Journal of Applied Physics, 2010Co-Authors: Changwook Jeong, Mark LundstromAbstract:The possibility of increasing the performance of thermionic cooling devices by relaxing lateral Momentum Conservation is examined. Upper limits for the ballistic emission current are established. It is then shown that for most cases, nonconserved lateral Momentum model produces a current that exceeds this upper limit. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, relaxing lateral Momentum may increase the current. These results can be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of conducting channels. They also show that within a thermionic emission framework, relaxing lateral Momentum Conservation does not increase the upper limit performance in most cases, and when it does, the increase is modest. More generally, however, especially when the connection to the carrier reservoir is poor and performance is well below the upper limit, relaxing la...
-
On Momentum Conservation and thermionic emission cooling
Journal of Applied Physics, 2010Co-Authors: Raseong Kim, Changwook Jeong, Mark LundstromAbstract:The possibility of increasing the performance of thermionic cooling devices by relaxing lateral Momentum Conservation is examined. Upper limits for the ballistic emission current are established. It is then shown that for most cases, nonconserved lateral Momentum model produces a current that exceeds this upper limit. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, relaxing lateral Momentum may increase the current. These results can be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of conducting channels. They also show that within a thermionic emission framework, relaxing lateral Momentum Conservation does not increase the upper limit performance in most cases, and when it does, the increase is modest. More generally, however, especially when the connection to the carrier reservoir is poor and performance is well below the upper limit, relaxing lateral Momentum Conservation could prove beneficial.
-
on Momentum Conservation and thermionic emission cooling
arXiv: Mesoscale and Nanoscale Physics, 2009Co-Authors: Raseong Kim, Changwook Jeong, Mark LundstromAbstract:The question of whether relaxing Momentum Conservation can increase the performance of thermionic cooling device is examined. Both homojunctions and heterojunctions are considered. It is shown that for many cases, a non-conserved lateral Momentum model overestimates the current. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, non-Conservation of lateral Momentum may increase the current. These results may be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of conducting channels. These results also show that within thermionic emission framework, the possibilities of increasing thermionic cooling by relaxing Momentum Conservation are limited. More generally, however, when the connection to the source is weak or in the presence of scattering, the situation may be different. Issues that deserve further study are identified.
Changwook Jeong - One of the best experts on this subject based on the ideXlab platform.
-
on Momentum Conservation and thermionic emission cooling
Journal of Applied Physics, 2010Co-Authors: Changwook Jeong, Mark LundstromAbstract:The possibility of increasing the performance of thermionic cooling devices by relaxing lateral Momentum Conservation is examined. Upper limits for the ballistic emission current are established. It is then shown that for most cases, nonconserved lateral Momentum model produces a current that exceeds this upper limit. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, relaxing lateral Momentum may increase the current. These results can be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of conducting channels. They also show that within a thermionic emission framework, relaxing lateral Momentum Conservation does not increase the upper limit performance in most cases, and when it does, the increase is modest. More generally, however, especially when the connection to the carrier reservoir is poor and performance is well below the upper limit, relaxing la...
-
On Momentum Conservation and thermionic emission cooling
Journal of Applied Physics, 2010Co-Authors: Raseong Kim, Changwook Jeong, Mark LundstromAbstract:The possibility of increasing the performance of thermionic cooling devices by relaxing lateral Momentum Conservation is examined. Upper limits for the ballistic emission current are established. It is then shown that for most cases, nonconserved lateral Momentum model produces a current that exceeds this upper limit. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, relaxing lateral Momentum may increase the current. These results can be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of conducting channels. They also show that within a thermionic emission framework, relaxing lateral Momentum Conservation does not increase the upper limit performance in most cases, and when it does, the increase is modest. More generally, however, especially when the connection to the carrier reservoir is poor and performance is well below the upper limit, relaxing lateral Momentum Conservation could prove beneficial.
-
on Momentum Conservation and thermionic emission cooling
arXiv: Mesoscale and Nanoscale Physics, 2009Co-Authors: Raseong Kim, Changwook Jeong, Mark LundstromAbstract:The question of whether relaxing Momentum Conservation can increase the performance of thermionic cooling device is examined. Both homojunctions and heterojunctions are considered. It is shown that for many cases, a non-conserved lateral Momentum model overestimates the current. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, non-Conservation of lateral Momentum may increase the current. These results may be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of conducting channels. These results also show that within thermionic emission framework, the possibilities of increasing thermionic cooling by relaxing Momentum Conservation are limited. More generally, however, when the connection to the source is weak or in the presence of scattering, the situation may be different. Issues that deserve further study are identified.
Justin M Shaw - One of the best experts on this subject based on the ideXlab platform.
-
controlling the polarization and vortex charge of attosecond high harmonic beams via simultaneous spin orbit Momentum Conservation
Nature Photonics, 2019Co-Authors: Kevin M Dorney, Laura Rego, Nathan J Brooks, Julio San Roman, Chenting Liao, Jennifer L Ellis, Dmitriy Zusin, Christian Gentry, Quynh Nguyen, Justin M ShawAbstract:Optical interactions are governed by both spin and angular Momentum Conservation laws, which serve as a tool for controlling light-matter interactions or elucidating electron dynamics and structure of complex systems. Here, we uncover a form of simultaneous spin and orbital angular Momentum Conservation and show, theoretically and experimentally, that this phenomenon allows for unprecedented control over the divergence and polarization of extreme-ultraviolet vortex beams. High harmonics with spin and orbital angular momenta are produced, opening a novel regime of angular Momentum Conservation that allows for manipulation of the polarization of attosecond pulses-from linear to circular-and for the generation of circularly polarized vortices with tailored orbital angular Momentum, including harmonic vortices with the same topological charge as the driving laser beam. Our work paves the way to ultrafast studies of chiral systems using high-harmonic beams with designer spin and orbital angular Momentum.
-
Controlling the polarization and vortex charge of attosecond high-harmonic beams via simultaneous spin–orbit Momentum Conservation
Nature photonics, 2018Co-Authors: Kevin M Dorney, Laura Rego, Nathan J Brooks, Chenting Liao, Jennifer L Ellis, Dmitriy Zusin, Christian Gentry, Quynh Nguyen, Julio San Roman, Justin M ShawAbstract:Optical interactions are governed by both spin and angular Momentum Conservation laws, which serve as a tool for controlling light-matter interactions or elucidating electron dynamics and structure of complex systems. Here, we uncover a form of simultaneous spin and orbital angular Momentum Conservation and show, theoretically and experimentally, that this phenomenon allows for unprecedented control over the divergence and polarization of extreme-ultraviolet vortex beams. High harmonics with spin and orbital angular momenta are produced, opening a novel regime of angular Momentum Conservation that allows for manipulation of the polarization of attosecond pulses-from linear to circular-and for the generation of circularly polarized vortices with tailored orbital angular Momentum, including harmonic vortices with the same topological charge as the driving laser beam. Our work paves the way to ultrafast studies of chiral systems using high-harmonic beams with designer spin and orbital angular Momentum.
Franz Gross - One of the best experts on this subject based on the ideXlab platform.
-
Gravitational coupling to two-particle bound states and Momentum Conservation in deep inelastic scattering
Physical Review D, 2000Co-Authors: Zoltan Batiz, Franz GrossAbstract:The Momentum Conservation sum rule for deep inelastic scattering (DIS) from composite particles is investigated using the general theory of relativity. For two (1+1)-dimensional examples, it is shown that covariant theories automatically satisy the DIS Momentum Conservation sum rule provided the bound state is covariantly normalized. Therefore, in these cases the two DIS sum rules for baryon Conservation and Momentum Conservation are equivalent. (c) 2000 The American Physical Society.
-
Gravitational coupling to two-particle bound states and Momentum Conservation in deep inelastic scattering
1999Co-Authors: Zoltan Batiz, Franz GrossAbstract:The Momentum Conservation sum rule for deep inelastic scattering (DIS) from composite particles is investigated using the general theory of relativity. For two 1+1 dimensional examples, it shown that covariant theories automatically satisfy the DIS Momentum Conservation sum rule provided the bound state is covariantly normalized. Therefore, in these cases, the two DIS sum rules for baryon Conservation and Momentum are equivalent.
M V Chekhova - One of the best experts on this subject based on the ideXlab platform.
-
microscale generation of entangled photons without Momentum Conservation
Physical Review Letters, 2019Co-Authors: Cameron Okoth, Andrea Cavanna, Tomas Santiagocruz, M V ChekhovaAbstract:We report, for the first time, the observation of spontaneous parametric down-conversion (SPDC) free of phase matching (Momentum Conservation). We alleviate the need to conserve Momentum by exploiting the position-Momentum uncertainty relation and using a planar geometry source, a $6\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ thick layer of lithium niobate. Nonphase-matched SPDC opens up a new platform on which to investigate fundamental quantum effects but it also has practical applications. The ultrasmall thickness leads to a frequency spectrum an order of magnitude broader than that of phase-matched SPDC. The strong two-photon correlations are still preserved due to energy Conservation. This results in ultrashort temporal correlation widths and huge frequency entanglement. The studies we make here can be considered as the initial steps into the emerging field of nonlinear quantum optics on the microscale and nanoscale.