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

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

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

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

5. 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?

6. 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:
1-100 µs

7. 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)! + -

8. 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

9. 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

10. 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)

11. Phase, rad

12. 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

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

14. Measuring the emission
Emission power (dBm)

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

16. Autler-Townes splittingΩ
ω12
probe
drive, Ω Ω Ω
ω01
drive, Ω
probe
ω01
ω12

18. 1 year 3 months ago:
today:

19. Thank you for the attention! Welcome to Russia!