Chalmers University of Technology Interaction between artificial atoms
Chalmers University of Technology Interaction between artificial atoms and microwaves Ø Introduction Ø Artificial atoms Ø Microwave reflection from a single atom Ø The photon router Ø Nonclassical microwaves Ø Atom in front of a mirror Experiments: Io. Chun Hoi , Chris Wilson, Tauno Palomaki Theory collaboration: Anton Frisk-Kockum, Borja Peropadre, Göran Johansson Per Delsing Quantum Device Physics
Chalmers University of Technology LT 28 conference 9 – 16 August 2017 Abstract submission 10 Apri l 2017 Early-bird registration Paper submission • • • 1 May 2017 15 June 2017 Invited speakers, prizes Oral and poster presentations Peer-reviewed proceedings in J. Phys. Conf. Series Subtopics 1. Quantum fluids and solids 2. Superconductivity 3. Cryogenic techniques and applications 4. Magnetism and quantum phase transitions 5. Quantum transport and quantum information in condensed matter www. LT 28. se Exhibitions Excursion, banquet Per Delsing Quantum Device Physics
Chalmers University of Technology Photons interacting with an artificial atom Qubit in a transmission line, interaction with microwave photons V 1+ V 2_ V 1 - Strong coupling 1 D-modes Large dipole moment ~5 GHz ~20 -50 m. K 10 um Per Delsing Quantum Device Physics
Chalmers University of Technology Outline Introduction An artificial atom Microwave reflection from a single atom The photon router Nonclassical microwaves Atom in front of a mirror Per Delsing Quantum Device Physics
Chalmers University of Technology Artificial atoms based on Josephson junctions Quantized electrical circuit Harmonic oscillator is not an atom Nonlinearity makes the circuit anharmonic and addressable Small JJ is a good nonlinear inductor Per Delsing Quantum Device Physics
Chalmers University of Technology The transmon qubit as an artificial atom A capacitively shunted Cooper-pair box E 01/h Jens Koch et. al. PRA (2007) Per Delsing Quantum Device Physics
Chalmers University of Technology Outline Introduction An artificial atom Microwave reflection from a single atom The photon router Nonclassical microwaves Atom in front of a mirror Per Delsing Quantum Device Physics
Chalmers University of Technology Transmission and Reflection coefficient Transmission coefficient On resonance, low power Similar experiments by Astafiev, et al. , NEC Science (2010). Per Delsing Quantum Device Physics
Chalmers University of Technology Reflection and exctinction Total extinction Constructive interference for the reflected wave Destructive interference for the transmitted wave Per Delsing Quantum Device Physics
Chalmers University of Technology Measurement set-up Measuring both transmission and reflection simultaneously System noise temperature ~6 K Per Delsing Quantum Device Physics
Chalmers University of Technology Transmission measurement Almost full transmission at high power Almost full reflection at low power Per Delsing Quantum Device Physics
Chalmers University of Technology Transmission measurement Magnitude Phase G 01/2π = 73 MHz, G 02/2π = 55 MHz, w 01/2π = 7. 1 GHz g 01/2π 18 MHz Per Delsing Quantum Device Physics
Chalmers University of Technology Two-Tone Spectroscopy Pumping the 0 -1 transition varying power probing transmission at low power varying f fprobe |2> |1> f 01 |0> Per Delsing Quantum Device Physics
Chalmers University of Technology Autler Townes splitting Pumping the 1 -2 transition, varying power probing the 0 -1 transition varying f Rabi dressed states fc =f 12 fprobe Autler Townes splitting, when Ω>G 01 Allows calibration of power at the sample Per Delsing Quantum Device Physics
Chalmers University of Technology Outline Introduction An artificial atom Micrrowave reflection from a single atom The photon router Nonclassical microwaves Atom in front of a mirror Per Delsing Quantum Device Physics
Chalmers University of Technology Single Photon Router A single photon gets reflected if no control pulse is sent When a control pulse is sent the first level is Rabi dressed and the photon is transmitted Output 1 Output 2 Signal in Control pulse Transmon qubit I. -C. Hoi et al. Physical Review Letters, 107, 073601 (2011) Per Delsing Quantum Device Physics
Chalmers University of Technology The On-Off ratio Sample 1 Rabi dressed states f 12 Sample 2 f 01 Rerouting a single photon with a fast pulse Per Delsing Quantum Device Physics
Chalmers University of Technology How fast is the router Transmission for different pulse times: 50 ns to 1µs 10 ns pulse times Routing photons on the 10 ns scale, Limited by 1/G 01 2 ns Strong coupling is good, this improves both speed and on/off ratio Per Delsing Quantum Device Physics
Chalmers University of Technology Cascading routers to a multiplexer Different anharmonicity for the different qubits Output 1 Output 2 Output 3 Output 4 Signal in Control pulse Per Delsing Quantum Device Physics
Chalmers University of Technology Outline Introduction An artificial atom Microwave reflection from a single atom The photon router Nonclassical microwaves Atom in front of a mirror Per Delsing Quantum Device Physics
Chalmers University of Technology Measuring the 2 nd order correlation function For optical frequencies there are single photon detectors Bozyigit, et al. Nature Physics, 7, 154 (2011) Per Delsing Quantum Device Physics
Chalmers University of Technology Comparing different sources Per Delsing Quantum Device Physics
Chalmers University of Technology Photon Number Filter Per Delsing Quantum Device Physics
Chalmers University of Technology Measuring correlations Per Delsing Quantum Device Physics
Chalmers University of Technology Testing the set-up, thermal versus coherent No free fitting parameters Per Delsing Quantum Device Physics
Chalmers University of Technology Measuring the transmitted field, bunching Per Delsing Quantum Device Physics
Chalmers University of Technology The reflected field, anti bunching g(2)(t) for two different powers Theory Non-idealities: Trigger jitter, T≠ 0, Circulator not perfect… Hoi et al. New J. Phys. (2012) Peropadre et al. New J. Phys. (2012) Per Delsing Quantum Device Physics
Chalmers University of Technology Outline Introduction An artificial atom Microwave reflection from a single atom The photon router Nonclassical microwaves Atom in front of a mirror Per Delsing Quantum Device Physics
Chalmers University of Technology Placing an atom in front of a mirror We place an “atom” (or superconducting qubit) on a chip We limit the electromagnetic field to one dimension A mirror is made by a thin metallic layer that shorts the electric field. We use a superconducting short in 1 D as a mirror. Per Delsing Quantum Device Physics
Chalmers University of Technology Placing an atom in front of a mirror Atom-mirror distance L=11 mm Sample layout Mode structure for L=l/2 and L=3 l/4 We can change the atom frequency, thus effectively changing the distance to the mirror, i. e. the distance measured in number of wavelengths. Per Delsing Quantum Device Physics
Chalmers University of Technology Measurement set-up The atom is placed at the distance L= 11 mm from the mirror. We measure microwave reflection from the atom/mirror system Per Delsing Quantum Device Physics
Chalmers University of Technology Doing spectroscopy on the “atom” Reflection at low power From the dip we can extract the relaxation rate G 1 and decoherence rate g Per Delsing Quantum Device Physics
Chalmers University of Technology Reflection from the atom and the mirror Nonlinear reflection of microwaves off the ”atom” At low power the microwaves are reflected from the atom. At high power the microwaves are reflected by the mirror On resonance Control experiment for relaxation rate G 1 and decoherence rate g Reflection: Magnitude and phase Reflection: Real and Imaginary Atom reflection Mirror reflection Per Delsing Quantum Device Physics
Chalmers University of Technology Doing spectroscopy on the “atom” Spectroscopy The ”atom” is invisible around 5. 4 GHz The quantum fluctuation from the transmission line and from the mirror interfere Per Delsing Extracting the relaxation rate T 1 differs by a factor of 10 Quantum Device Physics
Chalmers University of Technology Measuring the quantum fluctuations Quantum fluctuations are hard to measure since you cannot extract the energy. Spontaneous emission of an atom is caused by quantum fluctuations, so measuring the decay rate, we can indirectly measure the quantum fluctuations. The quantum fluctuation from the transmission line and from the mirror interfere Per Delsing Quantum Device Physics
Chalmers University of Technology Measuring the vacuum fluctuations as a function of the distance to the mirror Narrow range Wider range When the ”atom” is half a wavelength from the mirror the quantum fluctuations vanish (only for the atom-frequency) Probe power corresponds to 0. 04 photons Per Delsing I. -C. Hoi et al. , Nature Physics 11, 1045, (2015) Quantum Device Physics
Chalmers University of Technology Summary • Nonlinear reflection on an artificial atom • Demonstration of a Photon router with 99% on-off ratio • Nonclassical states • Probing and canceling vacuum fluctuations Hoi et al. Physical Review Letters, 107, 073601 (2011) Hoi et al. Physical Review Letters, 108, 263601 (2012) Hoi et al. Nature Physics, 11, 1045 (2015) Io. Chun Hoi Chris Wilson Tauno Palomaki Göran Johansson Per Delsing Borja Peropadre Anton Frisk-Kockum Quantum Device Physics
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