1 Experiments on Superconducting Metamaterial-Induced Transparency Cihan Kurter, John Abrahams, Chris Bennett, Tian Lan, Steven M. Anlage, L. Zhang, T. Koschny, C. Soukoulis (Ames/Iowa State) Alexander Zhuravel (Kharkov, Ukraine), Alexey Ustinov (KIT, Karlsruhe, Germany), Work Funded by NSF and ONR Metamaterials 2010, Karlsruhe, Germany 14 September, 2010

2 Metamaterial-Induced Transparency Inspired by: Electromagnetically-Induced Transparency (EIT) Light can be slowed, or even stopped at the EIT frequency L. V. Hau, Nature (1999) Fleischhauer, PRL (2000) N. Papasimakis, et al. Optics and Photonics News, Oct Classical Analog of EIT Garrido Alzar, et al., Am J Phys (2002) Strong dispersion with little loss 11 22 Dissipation  2 <<  1 to coherently drive particle 1 Atom Probe Field Pump Field Probe Frequency Probe Absorption

3 Re[x 1 (t)] Atom Probe Field Pump Field The “atom” has zero displacement at the EIT frequency, but large displacement for small de-tuning 11 22  2 <<  1  1 = 4.0 x  2 = 1.0 x Classical Analog of EIT The Importance of Strong Loss Contrast Absorbed Power

4 Metamaterial-Induced Transparency Work with L. Zhang, T. Koschny, and C. Soukoulis (Iowa State Univ.) Cu (radiative) Normal metal Nb (dark) Superconducting X-band waveguide Normal metal metamaterials: Papasimakis, PRL 2008 Tassin, PRL 2009 Superconducting Metamaterials 10 GHz E B Cu Nb 11 22

5 Simulation Results Metamaterial-Induced Transparency Index of Refraction Transmission and Reflection EIT Frequency Adjust coupling to dark resonators and frequencies of dark resonators to modify n(  ) dispersion L. Zhang, T. Koschny, and C. Soukoulis (Iowa State Univ.)

6 Experimental Setup Metamaterial-Induced Transparency Cryogenic Dewar X-band Waveguide Sample Network Analyzer Coaxial Cable 1 2

7 0 0 1()1() 2()2() 1()1()  2 (  ) ~ 1/      i   Superconductor Electrodynamics “binding energy” of Cooper pair ( 100 GHz ~ few THz) T = 0 ideal s-wave Surface Impedance (  > 0) Normal State Superconducting State (  < 2  ) Penetration depth (0) ~ 20 – 200 nm  n s e   m  Finite-temperature: X s (T) =  L =   (T) → ∞ as T →T c Narrow wire or thin film of thickness t : L(T) =   (T) coth(t/ (T)) →  0 2 (T)/t Kinetic Inductance Superfluid density 2 ~ m/n s T n s (T) TcTc 0 0 Normal State (T > T c ) (Drude Model) 1/  T  1 (T) TcTc 0 0 nn

8 Experimental Results Metamaterial-Induced Transparency Nb / Cu MM-EIT sample (first generation) in Cu waveguide EIT bandwidth (3 dB) = 7.5 MHz (~ 0.1%) P in = -30 dBm T = 4.6 K

9 Frequency (GHz) Transmission |S 21 |/|S 21 | max (dB) Superconducting Metamaterial-Induced Transparency Effect of Temperature on Transmission

10 Superconducting Metamaterial-Induced Transparency Effect of Temperature on Group Delay P in = -30 dBm

11 Experimental Results Metamaterial-Induced Transparency Switching/Limiting Behavior at High Power The “transparency window” switches off between +17 and +18 dBm

12 RF Power Dependence of Superconducting EIT Features To investigate the RF power dependence, we examine the RF current distributions in the superconducting parts of the sample using Laser Scanning Microscopy (LSM) See A. P. Zhuravel, et al., J. Appl. Phys. 108, (2010)

13 f = 9.63 GHz; P = 18 dBm; T = 7 K LSM Image of Superconducting RF Currents in EIT 10 GHz Upper Nb split ring Bottom Geometry 2D LSM image Focus on this corner Nb split ring Cu stripe Current flow numerical simulation, L. Zhang, et al. (Ames) C. Kurter, et al., arXiv:

14 RF Power Dependence of LSM Photoresponse in a Corner of the Nb Split Ring 15 dBm20 dBm 20.8 dBm21 dBm22 dBm 20.6 dBm Quartz substrate Nb film 100  m

15 Future Directions for Superconducting EIT Metamaterials Calibrated and de-embedded S 21 and group delay measurements Rounded-corner samples for better tunability at high power

16 Conclusions Demonstrated Superconducting Metamaterial-Induced Transparency Tunable with variable Kinetic Inductance and RF magnetic fields Demonstrated Tunability of  features: Temperature tuning (kinetic inductance → plasmonic regime) RF Magnetic Field tuning (magnetic Abrikosov vortices, J RF peaks) Superconducting Metamaterials Review Article (J. of Optics, in press): arXiv: Work Funded by NSF, ONR.

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19 Outline Losses in Metamaterials Review article on Superconducting Metamaterials (J. of Optics) arXiv: Brief Review of Superconductor Electrodynamics New Features Enabled by Superconductivity Low loss (+ inductance) enables very compact ‘atoms’ New sources of inductance New sources of nonlinearity and gain New ‘Atoms’ Some Novel Applications of Superconducting Metamaterials Future Prospects + Conclusions

20 Why Superconducting Metamaterials? The exciting novel applications of metamaterials: Flat-slab Imaging “Perfect” Imaging Cloaking Devices Illusion Optics etc. … SUPERCONDUCTING METAMATERIALS: Can achieve these requirements! … have strict REQUIREMENTS on the metamaterials: Low Losses Ultra-small size “atoms” (size << wavelength) Tunability / Texturing of the index of refraction n Cloaking Devices (Engheta, Leonhardt, Pendry, Milton) LHM RHM Point source “perfect image” Flat Lens Imaging Illusion Optics (Lai)

21 Outline Losses in Metamaterials Brief Review of Superconductor Electrodynamics New Features Enabled by Superconductivity Low loss (+ inductance) enables very compact ‘atoms’ New sources of inductance New sources of nonlinearity and gain New ‘Atoms’ Some Novel Applications of Superconducting Metamaterials Future Prospects + Conclusions

22 T  1 (T) TcTc 0 0 nn

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24 Frequency Absorption  2 = 1 x  2 = 1 x  2 = 1 x  1 = 4 x 10 -2

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26 Experimental Results Metamaterial-Induced Transparency This includes transmission losses in cold cables and waveguide Nb / Cu MM-EIT sample (first generation) in Cu waveguide

27 Experimental Results Metamaterial-Induced Transparency Switching/Limiting Behavior at High Power Frequency (GHz) |S 21 | (dB) The “transparency window” switches off between +17 and +18 dBm

28 Laser Scanning Microscopy of RF Currents Principle of the Measurement Work with A. Zhuravel (Kharkov) and A. Ustinov (Karlsruhe) P out f f0f0 |S 21 (f 0 )| 2 laser OFF laser ON co-planar resonator f 0 ~ 5.2 GHz P in modulated laser resonator transmission Local heating produces a change in transmission coefficient proportional to the local value of J RF 2 J. C. Culbertson, et al. J.Appl.Phys. 84, 2768 (1998) A. P. Zhuravel, et al., Appl.Phys.Lett. 81, 4979 (2002)  |S 12 | 2 ~ [ J RF (x,y)] 2 A 

29 1 mm T = 79.5 K f = GHz P = - 6 dBm 10  V 0  V 2-D Response Map for RF Current Distribution of a Sample Fundamental resonance mode (5.2 GHz) 8.5 mm RF photoresponse ~ J rf 2 (x, y) 240 nm thick film LAO

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31 T=79.5 K with 8672 A Generator P=-6 dBm in scale of 8672A F mod =99.99 kHz f= GHz Standing Wave J RF Pattern at Fundamental Frequency 2D image Photoresponse (a.u.) Fit: k fit = 0.39 mm -1 k theory = 0.42 mm -1 Proof that measured PR ~ J RF 2 to first order approx.