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Papers by Alexandre Blais

Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles... more Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles or radiation, in pure vacuum, virtual particles are constantly created and annihilated. In an electromagnetic field, the presence of virtual photons manifests itself as a small renormalization of the energy of a quantum system, known as the Lamb shift. We present an experimental

Physical Review Letters, 2010

We show that controlling relative phases of electromagnetic fields driving an atom with a Delta-c... more We show that controlling relative phases of electromagnetic fields driving an atom with a Delta-configuration energy-level structure enables optical susceptibility to be engineered in novel ways. In particular, relative-phase control can yield electromagnetically induced transparency but with the benefit that the transparency window is sandwiched between an absorption and an amplification band rather than between two absorption bands in typical

Superconducting circuit implementations of cavity QED have enabled the exploration of various reg... more Superconducting circuit implementations of cavity QED have enabled the exploration of various regimes of light-matter interaction. In this work, we present theoretical aspects of the observation of quantum properties of the field emitted from a cavity without access to non-linear/single-photon detectors (which have not been demonstrated reliably in the microwave regime). In particular, we focus on how to perform the

From Nanomechanics to Quantum Superconducting Circuits, 2012

Physical Review A, 2004

We propose a realizable architecture using one-dimensional transmission line resonators to reach ... more We propose a realizable architecture using one-dimensional transmission line resonators to reach the strong-coupling limit of cavity quantum electrodynamics in superconducting electrical circuits. The vacuum Rabi frequency for the coupling of cavity photons to quantized excitations of an adjacent electrical circuit (qubit) can easily exceed the damping rates of both the cavity and qubit. This architecture is attractive both as

Conference on Lasers and Electro-Optics/International Quantum Electronics Conference, 2009

Abstract We present the experimental implementation of two-qubit quantum algorithms in a supercon... more Abstract We present the experimental implementation of two-qubit quantum algorithms in a superconducting circuit. Our processor incorporates local and fast flux biasing of two transmon qubits within a circuit QED architecture. An off-resonant cavity bus shields the ...

Physical Review A, 2014

ABSTRACT In addition to their central role in quantum information processing, qubits have proven ... more ABSTRACT In addition to their central role in quantum information processing, qubits have proven to be useful tools in a range of other applications such as enhanced quantum sensing and as spectrometers of quantum noise. Here we show that a superconducting qubit strongly coupled to a nonlinear resonator can act as a probe of quantum fluctuations of the intraresonator field. Building on previous work [M. Boissoneault et al., Phys. Rev. A 85, 022305 (2012), 10.1103/PhysRevA.85.022305], we derive an effective master equation for the qubit which takes into account squeezing of the resonator field. We show how sidebands in the qubit excitation spectrum that are predicted by this model can reveal information about the squeezing factor r. The main results of this paper have already been successfully compared to experimental data [F. R. Ong et al., Phys. Rev. Lett. 110, 047001 (2013), 10.1103/PhysRevLett.110.047001], and we present here the details of the derivations.

Physical Review Letters, 2005

Physical Review Letters, 2011

Physical Review Letters, 2012

We demonstrate the realization of a hybrid solid-state quantum device, in which a semiconductor d... more We demonstrate the realization of a hybrid solid-state quantum device, in which a semiconductor double quantum dot is dipole coupled to the microwave field of a superconducting coplanar waveguide resonator. The double dot charge stability diagram extracted from measurements of the amplitude and phase of a microwave tone transmitted through the resonator is in good agreement with that obtained from transport measurements. Both the observed frequency shift and linewidth broadening of the resonator are explained considering the double dot as a charge qubit coupled with a strength of several tens of MHz to the resonator.

Physical Review Letters, 2011

Physical Review Letters, 2013

Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles... more Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles or radiation, in pure vacuum, virtual particles are constantly created and annihilated. In an electromagnetic field, the presence of virtual photons manifests itself as a small renormalization of the energy of a quantum system, known as the Lamb shift. We present an experimental

Physical Review Letters, 2010

We show that controlling relative phases of electromagnetic fields driving an atom with a Delta-c... more We show that controlling relative phases of electromagnetic fields driving an atom with a Delta-configuration energy-level structure enables optical susceptibility to be engineered in novel ways. In particular, relative-phase control can yield electromagnetically induced transparency but with the benefit that the transparency window is sandwiched between an absorption and an amplification band rather than between two absorption bands in typical

Superconducting circuit implementations of cavity QED have enabled the exploration of various reg... more Superconducting circuit implementations of cavity QED have enabled the exploration of various regimes of light-matter interaction. In this work, we present theoretical aspects of the observation of quantum properties of the field emitted from a cavity without access to non-linear/single-photon detectors (which have not been demonstrated reliably in the microwave regime). In particular, we focus on how to perform the

From Nanomechanics to Quantum Superconducting Circuits, 2012

Physical Review A, 2004

We propose a realizable architecture using one-dimensional transmission line resonators to reach ... more We propose a realizable architecture using one-dimensional transmission line resonators to reach the strong-coupling limit of cavity quantum electrodynamics in superconducting electrical circuits. The vacuum Rabi frequency for the coupling of cavity photons to quantized excitations of an adjacent electrical circuit (qubit) can easily exceed the damping rates of both the cavity and qubit. This architecture is attractive both as

Conference on Lasers and Electro-Optics/International Quantum Electronics Conference, 2009

Abstract We present the experimental implementation of two-qubit quantum algorithms in a supercon... more Abstract We present the experimental implementation of two-qubit quantum algorithms in a superconducting circuit. Our processor incorporates local and fast flux biasing of two transmon qubits within a circuit QED architecture. An off-resonant cavity bus shields the ...

Physical Review A, 2014

ABSTRACT In addition to their central role in quantum information processing, qubits have proven ... more ABSTRACT In addition to their central role in quantum information processing, qubits have proven to be useful tools in a range of other applications such as enhanced quantum sensing and as spectrometers of quantum noise. Here we show that a superconducting qubit strongly coupled to a nonlinear resonator can act as a probe of quantum fluctuations of the intraresonator field. Building on previous work [M. Boissoneault et al., Phys. Rev. A 85, 022305 (2012), 10.1103/PhysRevA.85.022305], we derive an effective master equation for the qubit which takes into account squeezing of the resonator field. We show how sidebands in the qubit excitation spectrum that are predicted by this model can reveal information about the squeezing factor r. The main results of this paper have already been successfully compared to experimental data [F. R. Ong et al., Phys. Rev. Lett. 110, 047001 (2013), 10.1103/PhysRevLett.110.047001], and we present here the details of the derivations.

Physical Review Letters, 2005

Physical Review Letters, 2011

Physical Review Letters, 2012

We demonstrate the realization of a hybrid solid-state quantum device, in which a semiconductor d... more We demonstrate the realization of a hybrid solid-state quantum device, in which a semiconductor double quantum dot is dipole coupled to the microwave field of a superconducting coplanar waveguide resonator. The double dot charge stability diagram extracted from measurements of the amplitude and phase of a microwave tone transmitted through the resonator is in good agreement with that obtained from transport measurements. Both the observed frequency shift and linewidth broadening of the resonator are explained considering the double dot as a charge qubit coupled with a strength of several tens of MHz to the resonator.

Physical Review Letters, 2011

Physical Review Letters, 2013