J. Aumentado - Academia.edu (original) (raw)
Papers by J. Aumentado
Physical Review Letters, 2016
Physical Review X, 2015
While quantum mechanics exquisitely describes the behavior of microscopic systems, one ongoing ch... more While quantum mechanics exquisitely describes the behavior of microscopic systems, one ongoing challenge is to explore its applicability to systems of larger size and mass. Unfortunately, quantum states of increasingly macroscopic objects are more easily corrupted by unintentional measurements from the classical environment. Additionally, even the intentional measurements from the observer can further perturb the system 1 . In optomechanics 2 , coherent light fields serve as the intermediary between the fragile mechanical states and our inherently classical world by exerting radiation pressure forces and extracting mechanical information. Here we engineer a microwave cavity optomechanical system 3 to stabilize a nonclassical steady-state of motion while independently, continuously, and nondestructively monitoring it. By coupling the motion of an aluminum membrane to two microwave cavities, we separately prepare and measure a squeezed state of motion 4 . We demonstrate a quantum nondemolition (QND) measurement 5-7 of sub-vacuum mechanical quadrature fluctuations. The techniques developed here have direct applications 8 in the areas of quantum-enhanced sensing 9 and quantum information processing, and could be further extended to more complex quantum states 10 .
Most Josephson parametric amplifiers are based on a resonant circuit architecture with associated... more Most Josephson parametric amplifiers are based on a resonant circuit architecture with associated bandwidth limitations. We examine the use of a `Josephson nonlinear fiber' -- a transmission line periodically loaded with Josephson junctions -- as an inherently broadband traveling wave parametric amplifier. We report on the device design, calculations of gain and bandwidth from a simple model, and preliminary measurement results. We acknowledge the ONR and the Hertz Foundation for financial support.
Nature Physics, 2015
Heisenberg's uncertainty principle results in one of the strangest quantum behaviors: an oscillat... more Heisenberg's uncertainty principle results in one of the strangest quantum behaviors: an oscillator can never truly be at rest. Even in its lowest energy state, at a temperature of absolute zero, its position and momentum are still subject to quantum fluctuations. Resolving these fluctuations using linear position measurements is complicated by the fact that classical noise can masquerade as quantum noise. On the other hand, direct energy detection of the oscillator in its ground state makes it appear motionless. So how can we resolve quantum fluctuations? Here, we parametrically couple a micromechanical oscillator to a microwave cavity to prepare the system in its quantum ground state and then amplify the remaining vacuum fluctuations into real energy quanta. Exploiting a superconducting qubit as a photon/phonon number resolving detector we provide the essential nonlinear resource to authenticate the unambiguously quantum nature of both light and motion. Our results further demonstrate the ability to control a long-lived mechanical oscillator using a non-Gaussian resource, directly enabling applications in quantum information processing and enhanced detection of displacement and forces.
Reservoir engineering in microwave cavity optomechanics FLO-RENT LECOCQ, JEREMY CLARK, JOSE AUMEN... more Reservoir engineering in microwave cavity optomechanics FLO-RENT LECOCQ, JEREMY CLARK, JOSE AUMENTADO, RAYMOND SIM-MONDS, JOHN TEUFEL, NIST Boulder -Microwave cavity optomechanics is an architecture in which a freely suspended membrane modulates the frequency of a superconducting microwave resonant circuit. The resulting parametric interactions influence both the mechanical degree of freedom and the microwave light emerging from the cavity. Even at cryogenic temperatures, the mechanical oscillator resonating at 10 MHz is typically dominated by its thermal reservoir, washing out any quantum behavior. However, in the presence of coherent drives to the cavity, the bare mechanical properties can be overwhelmed by the strong opto-mechanical interactions from the light field. By choosing wisely the frequency and amplitude of the drives, one can engineer the environment seen by the mechanical oscillator, a technique known as "reservoir engineering". From an experimentalist point of view, I will discuss how using two-tone driving schemes, we exploit correlations in the vacuum noise to: (1) eliminate the backaction imparted on the mechanical quadrature being measured, a technique so-called Back-Action Evasion, or (2) strongly couple the mechanical mode to a squeezed microwave bath.
Solid State Communications, 2003
We report measurements of the four terminal temperature dependent resistance of narrow Au wires i... more We report measurements of the four terminal temperature dependent resistance of narrow Au wires implanted with 100 ppm Fe impurities in proximity to superconducting Al films. The wires show an initial decrease in resistance as the temperature is lowered through the superconducting transition of the Al films, but then show an increase in resistance as the temperature is lowered further. In contrast to the case of pure Au wires in contact with a superconducting film, the resistance at the lowest temperatures rises above the normal state resistance. Analysis of the data shows that, in addition to contributions from magnetic scattering and electron -electron interactions, the temperature dependent resistivity shows a substantial contribution from the superconducting proximity effect, which exists even in the presence of strong spin scattering. Published by Elsevier Ltd.
New Journal of Physics, 2015
In this work we derive the general conditions for obtaining nonreciprocity in multi-mode parametr... more In this work we derive the general conditions for obtaining nonreciprocity in multi-mode parametrically-coupled systems. The results can be applied to a broad variety of optical, microwave, and hybrid systems including recent electro-and optomechanical devices. In deriving these results, we use a graph-based methodology to derive the scattering matrix. This approach naturally expresses the terms in the scattering coefficients as separate graphs corresponding to distinct coupling paths between modes such that it is evident that nonreciprocity arises as a consequence of multi-path interference and dissipation in key ancillary modes. These concepts facilitate the construction of new devices in which several other characteristics might also be simultaneously optimized. As an example, we synthesize a novel three-mode unilateral amplifier design by use of graphs. Finally, we analyze the isolation generated in a common parametric multi-mode system, the DC-SQUID.
Physical Review Letters, 2009
We calculate the energy decay rate of Josephson qubits and superconducting resonators from nonequ... more We calculate the energy decay rate of Josephson qubits and superconducting resonators from nonequilibrium quasiparticles. The decay rates from experiments are shown to be consistent with predictions based on a prior measurement of the quasiparticle density n(qp) = 10/microm(3), which suggests that nonequilibrium quasiparticles are an important decoherence source for Josephson qubits. Calculations of the energy-decay and diffusion of quasiparticles also indicate that prior engineered gap and trap structures, which reduce the density of quasiparticles, should be redesigned to improve their efficacy. This model also explains a striking feature in Josephson qubits and resonators-a small reduction in decay rate with increasing temperature.
Applied Physics Letters, 2015
Physical Review Letters, 2008
We observe a sharp threshold for dynamic phase locking in a high-Q transmission line resonator em... more We observe a sharp threshold for dynamic phase locking in a high-Q transmission line resonator embedded with a Josephson tunnel junction, and driven with a purely ac, chirped microwave signal. When the drive amplitude is below a critical value, which depends on the chirp rate and is sensitive to the junction critical current I0, the resonator is only excited near its linear resonance frequency. For a larger amplitude, the resonator phase locks to the chirped drive and its amplitude grows until a deterministic maximum is reached. Near threshold, the oscillator evolves smoothly in one of two diverging trajectories, providing a way to discriminate small changes in I0 with a nonswitching detector, with potential applications in quantum state measurement.
New Journal of Physics, 2014
ABSTRACT We explore the concept of nonreciprocity in coupled two-mode systems using a geometric m... more ABSTRACT We explore the concept of nonreciprocity in coupled two-mode systems using a geometric mapping to the Poincaré sphere. From this perspective, we recast the requirements for nonreciprocity in terms of rotation and inversion symmetry arguments for the vector describing the two-mode state. We provide a few examples (the microwave circulator, parametric up/down converter, and traveling wave frequency converter) to demonstrate how this general geometric picture can provide insight into specific physical systems.
Physica B: Condensed Matter, 2000
We have measured the magnetoresistance of submicron elliptical Ni particles with Au probes. In ad... more We have measured the magnetoresistance of submicron elliptical Ni particles with Au probes. In addition to the classical anisotropic magnetoresistance (AMR), we also observe conductance #uctuations and an asymmetry with respect to magnetic "eld which is associated with the four terminal nature of our measurements.
Physical Review B, 2003
... identical to that found in previous theoretical work for Josephson systems using environmenta... more ... identical to that found in previous theoretical work for Josephson systems using environmental and spin-boson models,9,2,8,10,11 we believe this paper is especially useful because the noisemodel gives a more physical description to the origins of the decoherence and can ...
New Journal of Physics, 2013
Physical Review B, 2003
... Such errors have been ob-served experimentally in five-and seven-junction pumps by Martinis e... more ... Such errors have been ob-served experimentally in five-and seven-junction pumps by Martinis et al.4,5,10 Other errors ... and present the equations that allow detailed simulation of its dynamics, including thermally activated tunneling, photon-assisted tunneling, and self-heating. ...
Physical Review Letters, 2016
Physical Review X, 2015
While quantum mechanics exquisitely describes the behavior of microscopic systems, one ongoing ch... more While quantum mechanics exquisitely describes the behavior of microscopic systems, one ongoing challenge is to explore its applicability to systems of larger size and mass. Unfortunately, quantum states of increasingly macroscopic objects are more easily corrupted by unintentional measurements from the classical environment. Additionally, even the intentional measurements from the observer can further perturb the system 1 . In optomechanics 2 , coherent light fields serve as the intermediary between the fragile mechanical states and our inherently classical world by exerting radiation pressure forces and extracting mechanical information. Here we engineer a microwave cavity optomechanical system 3 to stabilize a nonclassical steady-state of motion while independently, continuously, and nondestructively monitoring it. By coupling the motion of an aluminum membrane to two microwave cavities, we separately prepare and measure a squeezed state of motion 4 . We demonstrate a quantum nondemolition (QND) measurement 5-7 of sub-vacuum mechanical quadrature fluctuations. The techniques developed here have direct applications 8 in the areas of quantum-enhanced sensing 9 and quantum information processing, and could be further extended to more complex quantum states 10 .
Most Josephson parametric amplifiers are based on a resonant circuit architecture with associated... more Most Josephson parametric amplifiers are based on a resonant circuit architecture with associated bandwidth limitations. We examine the use of a `Josephson nonlinear fiber' -- a transmission line periodically loaded with Josephson junctions -- as an inherently broadband traveling wave parametric amplifier. We report on the device design, calculations of gain and bandwidth from a simple model, and preliminary measurement results. We acknowledge the ONR and the Hertz Foundation for financial support.
Nature Physics, 2015
Heisenberg's uncertainty principle results in one of the strangest quantum behaviors: an oscillat... more Heisenberg's uncertainty principle results in one of the strangest quantum behaviors: an oscillator can never truly be at rest. Even in its lowest energy state, at a temperature of absolute zero, its position and momentum are still subject to quantum fluctuations. Resolving these fluctuations using linear position measurements is complicated by the fact that classical noise can masquerade as quantum noise. On the other hand, direct energy detection of the oscillator in its ground state makes it appear motionless. So how can we resolve quantum fluctuations? Here, we parametrically couple a micromechanical oscillator to a microwave cavity to prepare the system in its quantum ground state and then amplify the remaining vacuum fluctuations into real energy quanta. Exploiting a superconducting qubit as a photon/phonon number resolving detector we provide the essential nonlinear resource to authenticate the unambiguously quantum nature of both light and motion. Our results further demonstrate the ability to control a long-lived mechanical oscillator using a non-Gaussian resource, directly enabling applications in quantum information processing and enhanced detection of displacement and forces.
Reservoir engineering in microwave cavity optomechanics FLO-RENT LECOCQ, JEREMY CLARK, JOSE AUMEN... more Reservoir engineering in microwave cavity optomechanics FLO-RENT LECOCQ, JEREMY CLARK, JOSE AUMENTADO, RAYMOND SIM-MONDS, JOHN TEUFEL, NIST Boulder -Microwave cavity optomechanics is an architecture in which a freely suspended membrane modulates the frequency of a superconducting microwave resonant circuit. The resulting parametric interactions influence both the mechanical degree of freedom and the microwave light emerging from the cavity. Even at cryogenic temperatures, the mechanical oscillator resonating at 10 MHz is typically dominated by its thermal reservoir, washing out any quantum behavior. However, in the presence of coherent drives to the cavity, the bare mechanical properties can be overwhelmed by the strong opto-mechanical interactions from the light field. By choosing wisely the frequency and amplitude of the drives, one can engineer the environment seen by the mechanical oscillator, a technique known as "reservoir engineering". From an experimentalist point of view, I will discuss how using two-tone driving schemes, we exploit correlations in the vacuum noise to: (1) eliminate the backaction imparted on the mechanical quadrature being measured, a technique so-called Back-Action Evasion, or (2) strongly couple the mechanical mode to a squeezed microwave bath.
Solid State Communications, 2003
We report measurements of the four terminal temperature dependent resistance of narrow Au wires i... more We report measurements of the four terminal temperature dependent resistance of narrow Au wires implanted with 100 ppm Fe impurities in proximity to superconducting Al films. The wires show an initial decrease in resistance as the temperature is lowered through the superconducting transition of the Al films, but then show an increase in resistance as the temperature is lowered further. In contrast to the case of pure Au wires in contact with a superconducting film, the resistance at the lowest temperatures rises above the normal state resistance. Analysis of the data shows that, in addition to contributions from magnetic scattering and electron -electron interactions, the temperature dependent resistivity shows a substantial contribution from the superconducting proximity effect, which exists even in the presence of strong spin scattering. Published by Elsevier Ltd.
New Journal of Physics, 2015
In this work we derive the general conditions for obtaining nonreciprocity in multi-mode parametr... more In this work we derive the general conditions for obtaining nonreciprocity in multi-mode parametrically-coupled systems. The results can be applied to a broad variety of optical, microwave, and hybrid systems including recent electro-and optomechanical devices. In deriving these results, we use a graph-based methodology to derive the scattering matrix. This approach naturally expresses the terms in the scattering coefficients as separate graphs corresponding to distinct coupling paths between modes such that it is evident that nonreciprocity arises as a consequence of multi-path interference and dissipation in key ancillary modes. These concepts facilitate the construction of new devices in which several other characteristics might also be simultaneously optimized. As an example, we synthesize a novel three-mode unilateral amplifier design by use of graphs. Finally, we analyze the isolation generated in a common parametric multi-mode system, the DC-SQUID.
Physical Review Letters, 2009
We calculate the energy decay rate of Josephson qubits and superconducting resonators from nonequ... more We calculate the energy decay rate of Josephson qubits and superconducting resonators from nonequilibrium quasiparticles. The decay rates from experiments are shown to be consistent with predictions based on a prior measurement of the quasiparticle density n(qp) = 10/microm(3), which suggests that nonequilibrium quasiparticles are an important decoherence source for Josephson qubits. Calculations of the energy-decay and diffusion of quasiparticles also indicate that prior engineered gap and trap structures, which reduce the density of quasiparticles, should be redesigned to improve their efficacy. This model also explains a striking feature in Josephson qubits and resonators-a small reduction in decay rate with increasing temperature.
Applied Physics Letters, 2015
Physical Review Letters, 2008
We observe a sharp threshold for dynamic phase locking in a high-Q transmission line resonator em... more We observe a sharp threshold for dynamic phase locking in a high-Q transmission line resonator embedded with a Josephson tunnel junction, and driven with a purely ac, chirped microwave signal. When the drive amplitude is below a critical value, which depends on the chirp rate and is sensitive to the junction critical current I0, the resonator is only excited near its linear resonance frequency. For a larger amplitude, the resonator phase locks to the chirped drive and its amplitude grows until a deterministic maximum is reached. Near threshold, the oscillator evolves smoothly in one of two diverging trajectories, providing a way to discriminate small changes in I0 with a nonswitching detector, with potential applications in quantum state measurement.
New Journal of Physics, 2014
ABSTRACT We explore the concept of nonreciprocity in coupled two-mode systems using a geometric m... more ABSTRACT We explore the concept of nonreciprocity in coupled two-mode systems using a geometric mapping to the Poincaré sphere. From this perspective, we recast the requirements for nonreciprocity in terms of rotation and inversion symmetry arguments for the vector describing the two-mode state. We provide a few examples (the microwave circulator, parametric up/down converter, and traveling wave frequency converter) to demonstrate how this general geometric picture can provide insight into specific physical systems.
Physica B: Condensed Matter, 2000
We have measured the magnetoresistance of submicron elliptical Ni particles with Au probes. In ad... more We have measured the magnetoresistance of submicron elliptical Ni particles with Au probes. In addition to the classical anisotropic magnetoresistance (AMR), we also observe conductance #uctuations and an asymmetry with respect to magnetic "eld which is associated with the four terminal nature of our measurements.
Physical Review B, 2003
... identical to that found in previous theoretical work for Josephson systems using environmenta... more ... identical to that found in previous theoretical work for Josephson systems using environmental and spin-boson models,9,2,8,10,11 we believe this paper is especially useful because the noisemodel gives a more physical description to the origins of the decoherence and can ...
New Journal of Physics, 2013
Physical Review B, 2003
... Such errors have been ob-served experimentally in five-and seven-junction pumps by Martinis e... more ... Such errors have been ob-served experimentally in five-and seven-junction pumps by Martinis et al.4,5,10 Other errors ... and present the equations that allow detailed simulation of its dynamics, including thermally activated tunneling, photon-assisted tunneling, and self-heating. ...