ABSTRACT Strong measurement of a quantum system can inhibit quantum state evolution, a phenomenon... more ABSTRACT Strong measurement of a quantum system can inhibit quantum state evolution, a phenomenon known as the quantum Zeno effect. If the measurement is not perfectly quantum non-demolition, it can also cause spurious transitions between states. We study these effects in a transmon qubit dispersively coupled to a superconducting microwave readout cavity. We use a fast, ultralow-noise parametric amplifier to amplify the microwave photons used to probe the qubit state, enabling continuous high-fidelity monitoring of the qubit. This arrangement allows us to observe quantum jumps between the qubit states in real time. We examine the dependence of the jump times on measurement strength and the qubit excitation protocol.
ABSTRACT We demonstrate continuous weak measurement of the state of a superconducting transmon qu... more ABSTRACT We demonstrate continuous weak measurement of the state of a superconducting transmon qubit in the circuit QED architecture using a Josephson parametric amplifier. The near quantum-limited noise performance of the amplifier enables us to obtain a high-fidelity measurement record which can be used to reconstruct the qubit state evolution during measurement by employing the quantum Bayesian formalism. While simultaneously driving the qubit at its Larmor frequency and measuring it weakly, we are able to resolve the spectral signature of Rabi oscillations present in the measurement record with a high signal-to-noise ratio (SNR). We discuss current limitations in this measurement scheme and suggest ways to further optimize the SNR. Our results suggest a route to implement quantum feedback to steer the state of a superconducting qubit.
We have fabricated superconducting microwave resonators in a lumped element geometry using single... more We have fabricated superconducting microwave resonators in a lumped element geometry using single crystal silicon dielectric parallel plate capacitors with C > 2 pF. Aluminum devices with resonant frequencies between 4.0 and 6.5 GHz exhibited an average internal quality factor Qi of 2 × 10 5 in the single photon excitation regime at T = 20 mK. Attributing the observed loss to the capacitive element, our measurements place and upper bound on the loss tangent of the silicon dielectric layer of tan δi = 5 × 10 −6. This level of loss is an order of magnitude lower than is currently observed in structures incorporating amorphous dielectric materials, thus making single crystal silicon capacitors an attractive, robust route for realizing long-lived quantum circuits.
We continuously measure the state of a superconducting quantum bit coupled to a microwave readout... more We continuously measure the state of a superconducting quantum bit coupled to a microwave readout cavity by using a fast, ultralow-noise parametric amplifier. This arrangement allows us to observe quantum jumps between the qubit states in real time, and should enable quantum error correction and feedback-essential components of quantum information processing.
Absorption/desorption kinetics of these composites at 100, 200 and 300 °C were measured. In all c... more Absorption/desorption kinetics of these composites at 100, 200 and 300 °C were measured. In all cases absorption rates increased with Cr 2 O 3 content at each temperature studied and absorption capacity decreased with decrease in temperature. Maximum hydrogen ...
We report an experiment on the determination of the quantum nondemolition (QND) nature of a reado... more We report an experiment on the determination of the quantum nondemolition (QND) nature of a readout scheme of a quantum electrical circuit. The circuit is a superconducting quantum bit measured by microwave reflectometry using a Josephson bifurcation amplifier. We ...
Lean burn engines have been promoted as a method to improve the fuel efficiency of automobile eng... more Lean burn engines have been promoted as a method to improve the fuel efficiency of automobile engines [1]. Impeding the widespread implementation of lean burn engines is the inability of current three-way catalytic converters to reduce nitrogen oxides (NO x ) under ...
We have constructed a new type of amplifier whose primary purpose is the readout of superconducti... more We have constructed a new type of amplifier whose primary purpose is the readout of superconducting quantum bits. It is based on the transition of an RF-driven Josephson junction between two distinct oscillation states near a dynamical bifurcation point. The main advantages of this new amplifier are speed, high-sensitivity, low back-action, and the absence of on-chip dissipation. Pulsed microwave reflection
The aim of the study was to carry out water quality assessment and to identify sources responsibl... more The aim of the study was to carry out water quality assessment and to identify sources responsible for deterioration of quality in the Malad creek, Mumbai, India. Creek receives sewage and wastewater from various drains and partially treated effluent from Malad and Versova treatment facilities. To assess the water quality, sampling locations were identified in the creek based on discharges of wastewater and sewage. Identified locations were traced in physical space by a global positioning system. Samples were collected during low and high tides and analyzed for physical, chemical and bacteriological parameters such as pH, Turbidity, DO, BOD, NH3-N, PO4 and FC and compared with SW-II Standards. Parameters were also analyzed statistically and correlated to determine the relationship amongst the parameters using SPSS software. The idea was to determine the probable causes contributing to the pollution in the creek. Various options were suggested for improvement in the creek quality based on water quality assessment.
ABSTRACT Strong measurement of a quantum system can inhibit quantum state evolution, a phenomenon... more ABSTRACT Strong measurement of a quantum system can inhibit quantum state evolution, a phenomenon known as the quantum Zeno effect. If the measurement is not perfectly quantum non-demolition, it can also cause spurious transitions between states. We study these effects in a transmon qubit dispersively coupled to a superconducting microwave readout cavity. We use a fast, ultralow-noise parametric amplifier to amplify the microwave photons used to probe the qubit state, enabling continuous high-fidelity monitoring of the qubit. This arrangement allows us to observe quantum jumps between the qubit states in real time. We examine the dependence of the jump times on measurement strength and the qubit excitation protocol.
ABSTRACT We demonstrate continuous weak measurement of the state of a superconducting transmon qu... more ABSTRACT We demonstrate continuous weak measurement of the state of a superconducting transmon qubit in the circuit QED architecture using a Josephson parametric amplifier. The near quantum-limited noise performance of the amplifier enables us to obtain a high-fidelity measurement record which can be used to reconstruct the qubit state evolution during measurement by employing the quantum Bayesian formalism. While simultaneously driving the qubit at its Larmor frequency and measuring it weakly, we are able to resolve the spectral signature of Rabi oscillations present in the measurement record with a high signal-to-noise ratio (SNR). We discuss current limitations in this measurement scheme and suggest ways to further optimize the SNR. Our results suggest a route to implement quantum feedback to steer the state of a superconducting qubit.
We have fabricated superconducting microwave resonators in a lumped element geometry using single... more We have fabricated superconducting microwave resonators in a lumped element geometry using single crystal silicon dielectric parallel plate capacitors with C > 2 pF. Aluminum devices with resonant frequencies between 4.0 and 6.5 GHz exhibited an average internal quality factor Qi of 2 × 10 5 in the single photon excitation regime at T = 20 mK. Attributing the observed loss to the capacitive element, our measurements place and upper bound on the loss tangent of the silicon dielectric layer of tan δi = 5 × 10 −6. This level of loss is an order of magnitude lower than is currently observed in structures incorporating amorphous dielectric materials, thus making single crystal silicon capacitors an attractive, robust route for realizing long-lived quantum circuits.
We continuously measure the state of a superconducting quantum bit coupled to a microwave readout... more We continuously measure the state of a superconducting quantum bit coupled to a microwave readout cavity by using a fast, ultralow-noise parametric amplifier. This arrangement allows us to observe quantum jumps between the qubit states in real time, and should enable quantum error correction and feedback-essential components of quantum information processing.
Absorption/desorption kinetics of these composites at 100, 200 and 300 °C were measured. In all c... more Absorption/desorption kinetics of these composites at 100, 200 and 300 °C were measured. In all cases absorption rates increased with Cr 2 O 3 content at each temperature studied and absorption capacity decreased with decrease in temperature. Maximum hydrogen ...
We report an experiment on the determination of the quantum nondemolition (QND) nature of a reado... more We report an experiment on the determination of the quantum nondemolition (QND) nature of a readout scheme of a quantum electrical circuit. The circuit is a superconducting quantum bit measured by microwave reflectometry using a Josephson bifurcation amplifier. We ...
Lean burn engines have been promoted as a method to improve the fuel efficiency of automobile eng... more Lean burn engines have been promoted as a method to improve the fuel efficiency of automobile engines [1]. Impeding the widespread implementation of lean burn engines is the inability of current three-way catalytic converters to reduce nitrogen oxides (NO x ) under ...
We have constructed a new type of amplifier whose primary purpose is the readout of superconducti... more We have constructed a new type of amplifier whose primary purpose is the readout of superconducting quantum bits. It is based on the transition of an RF-driven Josephson junction between two distinct oscillation states near a dynamical bifurcation point. The main advantages of this new amplifier are speed, high-sensitivity, low back-action, and the absence of on-chip dissipation. Pulsed microwave reflection
The aim of the study was to carry out water quality assessment and to identify sources responsibl... more The aim of the study was to carry out water quality assessment and to identify sources responsible for deterioration of quality in the Malad creek, Mumbai, India. Creek receives sewage and wastewater from various drains and partially treated effluent from Malad and Versova treatment facilities. To assess the water quality, sampling locations were identified in the creek based on discharges of wastewater and sewage. Identified locations were traced in physical space by a global positioning system. Samples were collected during low and high tides and analyzed for physical, chemical and bacteriological parameters such as pH, Turbidity, DO, BOD, NH3-N, PO4 and FC and compared with SW-II Standards. Parameters were also analyzed statistically and correlated to determine the relationship amongst the parameters using SPSS software. The idea was to determine the probable causes contributing to the pollution in the creek. Various options were suggested for improvement in the creek quality based on water quality assessment.
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Papers by Rajeev Vijay