Superconducting artificial atoms coupled to 1D open space Aleksei Dmitriev, PhD student LTS, 2017, Ischgl. PI: Prof. Oleg Astafiev

Egham, UK: Nanotech group London, UK: Quantum Detection group Dr. Vladimir Antonov Prof. Oleg Astafiev Dr. Rais Shaikhaidarov, Teresa Honigl-Decrinis Dr. Tobias Lidstrom

` Laboratory of Artificial Quantum Systems Moscow Institute of Physics and Technologies, Dolgoprudny, Moscow Region

Laboratory of Superconducting Metamaterials Prof. A. Ustinov Laboratory of Superconductivity Prof. V. Ryazanov

Issues Why microwave quantum optics with artificial atoms? Why qubit in free space, not in the resonator? Why does the qubit in free space live so short?

Quantum optics Strong coupling is desired: photon travels from cavity to atom many times and stays alive Could be implemented in different systems AAs coupled with light stronger than natural ones: fine constant is made small by Nature: 105- 106 1-100 µs 103 - 104

Let’s try something else Open Space Many bosonic modes… … or just a classical propagating field… … or quantum field but still propagating… No fixed frequency Flying photons Ultimate nonlinearity Multiplexed read-outc Absense of dispersive regime Light flights away fast Many modes of quantum noise No microwave single photon detectors (yet)! + -

Atom in open space Qubit acts as point-like scatterer of resonant field Artificial atom Artificial atoms are strongly coupled Natural atoms – weakly coupled to EM waves (weak scattering) Strong scattering of propagating waves A series of very promising applications

How to measure resonant scattering Drive RF coplanar line 50 Ω In resonance qubit acts as a point-like scatterer of radiation: Reflected wave interferes constructively Transmitted wave - destructively Amplification And detection

Transmission How about dynamics? T Power Transmission coef. Strong coupling (99% of extinction) Strong nonlinear regime of light-atom interaction How about dynamics? O. Astafiev et al. Science (2010)

Phase, rad

Dynamics of coherent emission Γ1 ≈ 5-15 MHz is restricted by quantum noise sensitivity Γ2 = Γ1/2 as follows from experiment. Emission Amplitude Inductive coupling (ask for details if needed) Trying to change design to obtain Γ1 ≈ 1 MHz  Yes, but extinction is worse then Large non-radiative relaxation

Asymmetric coupling 40 µm Сс = 0.3 fF, Ce = 3 fF System acts as a quantum emitter – single photons on demand

Measuring the emission Emission power (dBm)

Adding extra tones A. Yu. Dmitriev et al. JETP Lett (2017)

Autler-Townes splitting Ω ω12 probe drive, Ω Ω Ω ω01 drive, Ω probe ω01 ω12

1 year 3 months ago: today:

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