| 1. |
- Hoi, Io Chun, 1984, et al.
(författare)
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Giant Cross–Kerr Effect for Propagating Microwaves Induced by an Artificial Atom
- 2013
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 111:5, s. article nr. 053601-
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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.
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| 2. |
- Hoi, Io Chun, 1984, et al.
(författare)
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Demonstration of a Single-Photon Router in the Microwave Regime
- 2011
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 107:7
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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
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| 3. |
- Hoi, Io Chun, 1984, et al.
(författare)
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Generation of Nonclassical Microwave States Using an Artificial Atom in 1D Open Space
- 2012
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 108:26, s. art no. 263601-
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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.
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| 4. |
- Hoi, Io Chun, 1984, et al.
(författare)
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Microwave quantum optics with an artificial atom in one-dimensional open space
- 2013
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 15, s. Article Number: 025011 -
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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.
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| 5. |
- Palomaki, Tauno, 1979, et al.
(författare)
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Multilevel spectroscopy of two-level systems coupled to a dc SQUID phase qubit
- 2010
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 81:14, s. Art. no. 144503-
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Tidskriftsartikel (refereegranskat)abstract
- We report spectroscopic measurements of discrete two-level systems (TLSs) coupled to a dc superconducting quantum interference device phase qubit with a 16μ m 2 area Al/ AlO x /Al junction. Applying microwaves in the 10-11 GHz range, we found eight avoided level crossings with splitting sizes from 10 to 200 MHz and spectroscopic lifetimes from 4 to 160 ns. Assuming the transitions are from the ground state of the composite system to an excited state of the qubit or an excited state of one of the TLS states, we fit the location and spectral width to get the energy levels, splitting sizes, and spectroscopic coherence times of the phase qubit and TLSs. The distribution of splittings is consistent with noninteracting individual charged ions tunneling between random locations in the tunnel barrier and the distribution of lifetimes is consistent with the AlOx in the junction barrier having a frequency-independent loss tangent. To check that the charge of each TLS couples independently to the voltage across the junction, we also measured the spectrum in the 20-22 GHz range and found tilted avoided level crossings due to the second excited state of the junction and states in which both the junction and a TLS were excited.
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