We present a new millimeter wave optomechanical cavity intended to increase the vacuum optomechan... more We present a new millimeter wave optomechanical cavity intended to increase the vacuum optomechanical coupling rate towards the regime of single-photon quantum optome- chanics.
ABSTRACT We have investigated creep-like collective transport in pure and doped CDW conductor NbS... more ABSTRACT We have investigated creep-like collective transport in pure and doped CDW conductor NbSe_3. Below T_P/2 CDW motion between two driving threshold fields is characterized by extremely slow (nm/s) temperature activated and strongly field dependent velocities. The motion exhibits temporal order, as implied by observed highly coherent voltage oscillations. The creep velocity-field-temperature relation is consistent across all samples for velocities ranging over five orders of magnitude, but is inconsistent with all previously proposed functional forms for collective creep. The temperature dependence implies that motion is limited by processes with an energy scale comparable to the CDW gap. An apparent first-order dynamical transition from creep to high velocity sliding is associated with a characteristic velocity v_T^* and a frequency v_T^*/lambdac comparable to the estimated frequency of thermal activation over local strong pinning barriers, and can be completed in a CDW displacement of a single wavelength when the applied field is abruptly stepped above the transition field E_T^* corresponding to v_T^*.
A survey of experiments on charge and spin density wave conductors at low temperatures reveals co... more A survey of experiments on charge and spin density wave conductors at low temperatures reveals consistent behavior across disparate materials. This behavior illuminates the remarkable interplay between local and collective pinning and suggests a revised phase diagram for driven density wave systems.
Careful spectroscopic measurements of Josephson phase qubits have revealed avoided crossings char... more Careful spectroscopic measurements of Josephson phase qubits have revealed avoided crossings characteristic of the qubit interacting with a set of two-level resonators. As these extra splittings degrade the quality of the qubit, it is extremely important to characterize and understand their origin. We will present data from a variety of qubits that show these resonators have an amplitude probability distribution which scales inversely with splitting magnitude up to a certain splitting size. This data can be explained with a model based on two-level critical-current fluctuators in the junction. This model is also reasonably consistent with previous measurements of 1/f (low frequency) critical-current noise.
Madison-We have probed charge density wave (CDW) structure in stepped, whisker-like NbSe 3 sample... more Madison-We have probed charge density wave (CDW) structure in stepped, whisker-like NbSe 3 samples with lateral variations of pinning strength by X-ray microbeam diffraction using 2-ID-D beamline at APS-ANL. The rotation of the CDW q-vector on the depinned side appears above the threshold field for CDW depinning, consistent with the picture of inhomogeneous pinning. The corresponding shear strain profile is determined with a resolution of 300 nm. The results demonstrate how the magnitude of shear strains changes with the DC bias applied along the direction of CDW motion. This profile is compared with finite element modeling.
Quantum entanglement of mechanical systems emerges when distinct objects move with such a high de... more Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 pg. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are uniquely poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.
Quantum entanglement of mechanical systems emerges when distinct objects move with such a high de... more Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 picograms. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.
Nonreciprocal transmission and isolation at microwave frequencies are important in many practical... more Nonreciprocal transmission and isolation at microwave frequencies are important in many practical applications. In particular, compact isolators are useful in protecting sensitive quantum circuits operating at cryogenic temperatures from amplifier backaction and other environmental noise such as black-body radiation from higher temperature stages. However, the size of commercial cryogenic isolators limits the ability to measure multiple quantum circuits because of space constraints in typical dilution refrigerator systems. Furthermore, isolators usually require the use of ferrite components that cannot be integrated at the chip level and, since they also need large biasing magnetic fields, are incompatible with superconducting quantum circuits. In this work we show one way to accomplish isolation in a superconducting chip-scale device, a traveling-wave unidirectional frequency converter based on a parametrically pumped superconducting Josephson-junction transmission line, demonstrating better than 4.8 dB of inferred signal isolation from 6.6 to 11.4 GHz, with a maximum of 12 dB at 9.5 GHz. By using frequency diplexing techniques a conventional isolator could be implemented over this bandwidth.
We will present preliminary results on fabrication and characterization of the mechanical propert... more We will present preliminary results on fabrication and characterization of the mechanical properties freely suspended aluminum membranes at ultralow temperatures. The radio-frequency vibrational modes are detected by dispersively coupling membranes to superconducting microwave ...
ABSTRACT A metastable phase qubit was measured using a tunable cavity by two methods: a tunneling... more ABSTRACT A metastable phase qubit was measured using a tunable cavity by two methods: a tunneling measurement followed by magnetometry readout by the cavity, and a non-destructive dispersive measurement of the qubit by the cavity. The cavity was also used to directly observe the photons radiated by a tunneling measurement. Using a tunable cavity to dispersively measure a metastable phase qubit avoids tunneling measurement radiation and allows for further post-measurement qubit manipulations, two characteristics useful in a quantum processor. The tunable nature of the cavity allows it to be detuned during any single qubit or multi-qubit gate operations in order to main long qubit lifetimes by avoiding loss via the Purcell Effect. This architecture is readily expanded for multiplexed readout of many qubits.
ABSTRACT Recent theoretical and experimental study has suggested the potential of mesoscale exper... more ABSTRACT Recent theoretical and experimental study has suggested the potential of mesoscale experiments for probing charge-density-wave (CDW) physics. Characteristic CDW correlation lengths are on the order of microns, which makes fabrication of mesostructures straightforward. We evaluated the effects of fabrication processing (etching, patterning, heating, exposure to chemical agents) on CDW transport properties of high quality NbSe3 crystals. The crystal thickness can be controlled over a wide range and the obtained patterned crystals still retain highly "clean" CDW transport characteristics. We removed preexisting thickness steps from some crystals and intentionally patterned longitudinal thickness steps along the crystal chain direction on others to study size-related CDW shear and finite size effects. By dry etching we produced extremely thin NbSe3 crystals and used these to fabricate MOSFET-like devices. These allow the effects of crystal thickness on the modulation of the CDW threshold field by the gate bias to be examined.
The standard amorphous AlO$_{x}$ tunnel barriers in superconducting qubits contain many nanoscopi... more The standard amorphous AlO$_{x}$ tunnel barriers in superconducting qubits contain many nanoscopic fluctuators. These nanoscopic fluctuators destroy the coherent quantum information stored in the qubit. Recently, we eliminated 80{\%} of these fluctuators using single-crystal ...
We present a new millimeter wave optomechanical cavity intended to increase the vacuum optomechan... more We present a new millimeter wave optomechanical cavity intended to increase the vacuum optomechanical coupling rate towards the regime of single-photon quantum optome- chanics.
ABSTRACT We have investigated creep-like collective transport in pure and doped CDW conductor NbS... more ABSTRACT We have investigated creep-like collective transport in pure and doped CDW conductor NbSe_3. Below T_P/2 CDW motion between two driving threshold fields is characterized by extremely slow (nm/s) temperature activated and strongly field dependent velocities. The motion exhibits temporal order, as implied by observed highly coherent voltage oscillations. The creep velocity-field-temperature relation is consistent across all samples for velocities ranging over five orders of magnitude, but is inconsistent with all previously proposed functional forms for collective creep. The temperature dependence implies that motion is limited by processes with an energy scale comparable to the CDW gap. An apparent first-order dynamical transition from creep to high velocity sliding is associated with a characteristic velocity v_T^* and a frequency v_T^*/lambdac comparable to the estimated frequency of thermal activation over local strong pinning barriers, and can be completed in a CDW displacement of a single wavelength when the applied field is abruptly stepped above the transition field E_T^* corresponding to v_T^*.
A survey of experiments on charge and spin density wave conductors at low temperatures reveals co... more A survey of experiments on charge and spin density wave conductors at low temperatures reveals consistent behavior across disparate materials. This behavior illuminates the remarkable interplay between local and collective pinning and suggests a revised phase diagram for driven density wave systems.
Careful spectroscopic measurements of Josephson phase qubits have revealed avoided crossings char... more Careful spectroscopic measurements of Josephson phase qubits have revealed avoided crossings characteristic of the qubit interacting with a set of two-level resonators. As these extra splittings degrade the quality of the qubit, it is extremely important to characterize and understand their origin. We will present data from a variety of qubits that show these resonators have an amplitude probability distribution which scales inversely with splitting magnitude up to a certain splitting size. This data can be explained with a model based on two-level critical-current fluctuators in the junction. This model is also reasonably consistent with previous measurements of 1/f (low frequency) critical-current noise.
Madison-We have probed charge density wave (CDW) structure in stepped, whisker-like NbSe 3 sample... more Madison-We have probed charge density wave (CDW) structure in stepped, whisker-like NbSe 3 samples with lateral variations of pinning strength by X-ray microbeam diffraction using 2-ID-D beamline at APS-ANL. The rotation of the CDW q-vector on the depinned side appears above the threshold field for CDW depinning, consistent with the picture of inhomogeneous pinning. The corresponding shear strain profile is determined with a resolution of 300 nm. The results demonstrate how the magnitude of shear strains changes with the DC bias applied along the direction of CDW motion. This profile is compared with finite element modeling.
Quantum entanglement of mechanical systems emerges when distinct objects move with such a high de... more Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 pg. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are uniquely poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.
Quantum entanglement of mechanical systems emerges when distinct objects move with such a high de... more Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 picograms. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.
Nonreciprocal transmission and isolation at microwave frequencies are important in many practical... more Nonreciprocal transmission and isolation at microwave frequencies are important in many practical applications. In particular, compact isolators are useful in protecting sensitive quantum circuits operating at cryogenic temperatures from amplifier backaction and other environmental noise such as black-body radiation from higher temperature stages. However, the size of commercial cryogenic isolators limits the ability to measure multiple quantum circuits because of space constraints in typical dilution refrigerator systems. Furthermore, isolators usually require the use of ferrite components that cannot be integrated at the chip level and, since they also need large biasing magnetic fields, are incompatible with superconducting quantum circuits. In this work we show one way to accomplish isolation in a superconducting chip-scale device, a traveling-wave unidirectional frequency converter based on a parametrically pumped superconducting Josephson-junction transmission line, demonstrating better than 4.8 dB of inferred signal isolation from 6.6 to 11.4 GHz, with a maximum of 12 dB at 9.5 GHz. By using frequency diplexing techniques a conventional isolator could be implemented over this bandwidth.
We will present preliminary results on fabrication and characterization of the mechanical propert... more We will present preliminary results on fabrication and characterization of the mechanical properties freely suspended aluminum membranes at ultralow temperatures. The radio-frequency vibrational modes are detected by dispersively coupling membranes to superconducting microwave ...
ABSTRACT A metastable phase qubit was measured using a tunable cavity by two methods: a tunneling... more ABSTRACT A metastable phase qubit was measured using a tunable cavity by two methods: a tunneling measurement followed by magnetometry readout by the cavity, and a non-destructive dispersive measurement of the qubit by the cavity. The cavity was also used to directly observe the photons radiated by a tunneling measurement. Using a tunable cavity to dispersively measure a metastable phase qubit avoids tunneling measurement radiation and allows for further post-measurement qubit manipulations, two characteristics useful in a quantum processor. The tunable nature of the cavity allows it to be detuned during any single qubit or multi-qubit gate operations in order to main long qubit lifetimes by avoiding loss via the Purcell Effect. This architecture is readily expanded for multiplexed readout of many qubits.
ABSTRACT Recent theoretical and experimental study has suggested the potential of mesoscale exper... more ABSTRACT Recent theoretical and experimental study has suggested the potential of mesoscale experiments for probing charge-density-wave (CDW) physics. Characteristic CDW correlation lengths are on the order of microns, which makes fabrication of mesostructures straightforward. We evaluated the effects of fabrication processing (etching, patterning, heating, exposure to chemical agents) on CDW transport properties of high quality NbSe3 crystals. The crystal thickness can be controlled over a wide range and the obtained patterned crystals still retain highly "clean" CDW transport characteristics. We removed preexisting thickness steps from some crystals and intentionally patterned longitudinal thickness steps along the crystal chain direction on others to study size-related CDW shear and finite size effects. By dry etching we produced extremely thin NbSe3 crystals and used these to fabricate MOSFET-like devices. These allow the effects of crystal thickness on the modulation of the CDW threshold field by the gate bias to be examined.
The standard amorphous AlO$_{x}$ tunnel barriers in superconducting qubits contain many nanoscopi... more The standard amorphous AlO$_{x}$ tunnel barriers in superconducting qubits contain many nanoscopic fluctuators. These nanoscopic fluctuators destroy the coherent quantum information stored in the qubit. Recently, we eliminated 80{\%} of these fluctuators using single-crystal ...
Uploads
Papers by Katarina Cicak