| 1. |
- Hoi, Io Chun, 1984, et al.
(författare)
-
Generation of Nonclassical Microwave States Using an Artificial Atom in 1D Open Space
- 2012
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 108:26, s. art no. 263601-
-
Tidskriftsartikel (refereegranskat)abstract
- We have embedded an artificial atom, a superconducting transmon qubit, in a 1D open space and investigated the scattering properties of an incident microwave coherent state. By studying the statistics of the reflected and transmitted fields, we demonstrate that the scattered states can be nonclassical. In particular, by measuring the second-order correlation function, g(2), we show photon antibunching in the reflected field and superbunching in the transmitted field. We also compare the elastically and inelastically scattered fields using both phase-sensitive and phase-insensitive measurements.
|
|
| 2. |
- Hoi, Io Chun, 1984, et al.
(författare)
-
Giant Cross–Kerr Effect for Propagating Microwaves Induced by an Artificial Atom
- 2013
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 111:5, s. article nr. 053601-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the effective interaction between two microwave fields, mediated by a transmon-type superconducting artificial atom which is strongly coupled to a coplanar transmission line. The interaction between the fields and atom produces an effective cross–Kerr coupling. We demonstrate average cross–Kerr phase shifts of up to 20 degrees per photon with both coherent microwave fields at the single-photon level. Our results provide an important step toward quantum applications with propagating microwave photons.
|
|
| 3. |
- Hoi, Io Chun, 1984, et al.
(författare)
-
Microwave quantum optics with an artificial atom in one-dimensional open space
- 2013
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 15, s. Article Number: 025011 -
-
Tidskriftsartikel (refereegranskat)abstract
- We address recent advances in microwave quantum optics with artificial atoms in one-dimensional (1D) open space. This field relies on the fact that the coupling between a superconducting artificial atom and propagating microwave photons in a 1D open transmission line can be made strong enough to observe quantum coherent effects, without using any cavity to confine the microwave photons. We investigate the scattering properties in such a system with resonant coherent microwaves. We observe the strong nonlinearity of the artificial atom and under strong driving we observe the Mollow triplet. By applying two resonant tones, we also observe the Autler-Townes splitting. Exploiting these effects, we demonstrate two quantum devices at the single-photon level in the microwave regime: the single-photon router and the photon-dnumber filter. These devices provide important steps toward the realization of an on-chip quantum network.
|
|
| 4. |
- Peropadre, B., et al.
(författare)
-
Scattering of coherent states on a single artificial atom
- 2013
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 15, s. Article Number: 035009-
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we theoretically analyze a circuit quantum electrodynamics design where propagating quantum microwaves interact with a single artificial atom, a single Cooper-pair box. In particular, we derive a master equation in the so-called transmon regime, including coherent drives. Inspired by recent experiments, we then apply the master equation to describe the dynamics in both a two-level and a three-level approximation of the atom. In the two-level case, we also discuss how to measure photon antibunching in the reflected field and how it is affected by finite temperature and finite detection bandwidth.
|
|
| 5. |
- Staudt, Matthias, 1977, et al.
(författare)
-
Coupling of an erbium spin ensemble to a superconducting resonator
- 2012
-
Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 1361-6455 .- 0953-4075. ; 45:12, s. Art. no. 124019-
-
Tidskriftsartikel (refereegranskat)abstract
- A quantum coherent interface between optical and microwave photons can be used as a basic building block within a future quantum information network. The interface is envisioned as an ensemble of rare-earth ions coupled to a superconducting resonator, allowing for coherent transfer between optical and microwave photons. Towards this end, we have realized a hybrid device coupling a Er3+-doped Y2SiO5 crystal in a superconducting coplanar waveguide cavity. We observe a collective spin coupling of 4 MHz and a spin linewidth of down to 75 MHz.
|
|
| 6. |
- Cheng, Yu Ting, et al.
(författare)
-
Tuning atom-field interaction via phase shaping
- 2024
-
Ingår i: Physical Review A. - 2469-9934 .- 2469-9926. ; 109:2
-
Tidskriftsartikel (refereegranskat)abstract
- A coherent electromagnetic field can be described by its amplitude, frequency, and phase. All these properties can influence the interaction between the field and an atom. Here we demonstrate the phase shaping of microwaves that are scattered by a superconducting artificial atom coupled to the end of a semi-infinite one-dimensional transmission line. In particular, we input a weak exponentially rising pulse with phase modulation to a transmon qubit. We observe that atom-field interaction can be tuned from a nearly full interaction (interaction efficiency, i.e., amount of the field energy interacting with the atom, of 94.5 %) to effectively no interaction (interaction efficiency of 3.5 %).
|
|
| 7. |
- Fan, B. X., et al.
(författare)
-
Breakdown of the Cross-Kerr Scheme for Photon Counting
- 2013
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 110:5
-
Tidskriftsartikel (refereegranskat)abstract
- We show, in the context of single-photon detection, that an atomic three-level model for a transmon in a transmission line does not support the predictions of the nonlinear polarizability model known as the cross-Kerr effect. We show that the induced displacement of a probe in the presence or absence of a single photon in the signal field, cannot be resolved above the quantum noise in the probe. This strongly suggests that cross-Kerr media are not suitable for photon counting or related single-photon applications. Our results are presented in the context of a transmon in a one-dimensional microwave waveguide, but the conclusions also apply to optical systems.
|
|
| 8. |
- Hoi, Io Chun, 1984, et al.
(författare)
-
Demonstration of a Single-Photon Router in the Microwave Regime
- 2011
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 107:7
-
Tidskriftsartikel (refereegranskat)abstract
- We have embedded an artificial atom, a superconducting transmon qubit, in an open transmission line and investigated the strong scattering of incident microwave photons (similar to 6 GHz). When an input coherent state, with an average photon number N
|
|
| 9. |
- Hoi, Io Chun, 1984, et al.
(författare)
-
Probing the quantum vacuum with an artificial atom in front of a mirror
- 2015
-
Ingår i: Nature Physics. - 1745-2481 .- 1745-2473. ; 11:12, s. 1045-1049
-
Tidskriftsartikel (refereegranskat)abstract
- Quantum fluctuations of the vacuum are both a surprising and fundamental phenomenon of nature. Understood as virtual photons, they still have a very real impact, for instance, in the Casimir effects and the lifetimes of atoms. Engineering vacuum fluctuations is therefore becoming increasingly important to emerging technologies. Here, we shape vacuum fluctuations using a superconducting circuit analogue of a mirror, creating regions in space where they are suppressed. Moving an artificial atom through these regions and measuring the spontaneous emission lifetime of the atom provides us with the spectral density of the vacuum fluctuations. Using the paradigm of waveguide quantum electrodynamics, we significantly improve over previous studies of the interaction of an atom with its mirror image, observing a spectral density as low as 0.02 quanta, a factor of 50 below the mirrorless result. This demonstrates that we can hide the atom from the vacuum, even though it is exposed in free space.
|
|
| 10. |
- Hoi, Io Chun, 1984
(författare)
-
Quantum Optics with Propagating Microwaves in Superconducting Circuits
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- We address recent advances in quantum optics with propagating microwavesin superconducting circuits. This research field exploits on the fact that the coupling between a superconducting artificial atom and propagating microwave photons in a one-dimensional (1D) open transmission line can be made strong enough to observe quantum effects, without using any cavity to confine the microwave photons.We embed an artificial atom, a superconducting transmon qubit, in a 1D opentransmission line and investigate the scattering properties of coherent microwaves. When an input coherent state, with an average photon number much less than 1, is on resonance with the artificial atom, we observe extinction of up to 99% in the forward propagating field. We observe the strong nonlinearity of the artificial atom and under strong driving we observe the Mollow triplet. We also study the statistics of the reflected and transmitted beams, which are predicted to be nonclassical states. In particular, we demonstrate photon antibunching in the reflected beam by measuring the second-order correlation function. By applying a second control tone, we observe the Autler-Townes splitting and a giant cross-Kerr effect.Furthermore, we demonstrate fast operation of a single-photon router usingthe Autler-Townes splitting. This device provides important steps towards the realization of a quantum network. This thesis describes the motivation, theoretical background, design, implementation and measurement results.
|
|
