Experiments on Superconducting MetamaterialInduced Transparency Cihan Kurter John

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 1

Metamaterial-Induced Transparency Inspired by: Electromagnetically-Induced Transparency (EIT) Probe Absorption Strong dispersion with little loss Probe Frequency Probe Field Pump Field Classical Analog of EIT Garrido Alzar, et al. , Am J Phys (2002) Dissipation g 2 << g 1 to coherently drive particle 1 Probe Frequency N. Papasimakis, et al. Optics and Photonics News, Oct. 2009 Atom g 2 g 1 Light can be slowed, or even stopped at the EIT frequency L. V. Hau, Nature (1999) Fleischhauer, PRL (2000) 2

Classical Analog of EIT The Importance of Strong Loss Contrast g 1 g 2 Pump Field Re[x 1(t)] Atom The “atom” has zero displacement at the EIT frequency, but large displacement for small de-tuning Absorbed Power Probe Field 3 g 2 << g 1 = 4. 0 x 10 -2 g 2 = 1. 0 x 10 -7

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

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

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

Superconductor Electrodynamics s 1( w ) s = s 1 -is 2 l 2 ~ m/ns 0 (Drude Model) s 2( w ) (p nse 2/m)d(w) Superfluid density s 2(w) ~ 1/w T=0 ideal s-wave ns(T) Normal State (T > Tc) s 1( w ) 0 1/t 0 w Tc 0 sn s 1(T) “binding energy” of Cooper pair (100 GHz ~ few THz) T 0 0 Tc T Surface Impedance (w > 0) Normal State Superconducting State (w < 2 D) Penetration depth l(0) ~ 20 – 200 nm Finite-temperature: Xs(T) = w. L = wm 0 l(T) → ∞ as T →Tc 7 Narrow wire or thin film of thickness t : L(T) = m 0 l(T) coth(t/l(T)) → m 0 l 2(T)/t Kinetic Inductance

Experimental Results Metamaterial-Induced Transparency Pin = -30 d. Bm T = 4. 6 K 8 Nb / Cu MM-EIT sample (first generation) in Cu waveguide EIT bandwidth (3 d. B) = 7. 5 MHz (~ 0. 1%)

Superconducting Metamaterial-Induced Transparency Effect of Temperature on Transmission |S 21|/|S 21|max (d. B) 0 -5 -10 -15 -20 -25 Frequency (GHz) 9

Superconducting Metamaterial-Induced Transparency Effect of Temperature on Group Delay Pin = -30 d. Bm 10

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

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, 033920 (2010) 12

LSM Image of Superconducting RF Currents in EIT sample @ 10 GHz Geometry Nb split ring 2 D LSM image Focus on this corner Upper Nb split ring f = 9. 63 GHz; P = 18 d. Bm; T = 7 K Cu stripe Bottom Current flow numerical simulation, L. Zhang, et al. (Ames) 13 C. Kurter, et al. , ar. Xiv: 1008. 2020

RF Power Dependence of LSM Photoresponse in a Corner of the Nb Split Ring Nb film 0 m 10 m 14 Quartz substrate 0 m 10 m 15 d. Bm 20. 6 d. Bm 20. 8 d. Bm 21 d. Bm 22 d. Bm

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

Conclusions Demonstrated Superconducting Metamaterial-Induced Transparency Tunable with variable Kinetic Inductance and RF magnetic fields Demonstrated Tunability of EIT features: Temperature tuning (kinetic inductance → plasmonic regime) RF Magnetic Field tuning (magnetic Abrikosov vortices, JRF peaks) Superconducting Metamaterials Review Article (J. of Optics, in press): ar. Xiv: 1004. 3226 Work Funded by NSF, ONR. 16

Cryo. Coolers and Cryo. Packaging Small, inexpensive and reliable cryocoolers are available Stirling cycle cryocooler +compressor! MTBF > 106 hours 2. 8 kg 92 mm OD x 300 mm 5 W cooling power @ 77 K STI “Amp. Link” Filter 1850 – 1910 MHz PCS band 17 Many companies build cryo-cooled microwave and high-speed digital products

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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 Review article on Superconducting Metamaterials (J. of Optics) ar. Xiv: 1004. 3226 19

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

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 21

sn s 1(T) 0 22 0 Tc T

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Absorption g 2 = 1 x 10 -2 g 2 = 1 x 10 -3 g 1 = 4 x 10 -2 g 2 = 1 x 10 -7 Frequency 24

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

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

Laser Scanning Microscopy of RF Currents Principle of the Measurement Work with A. Zhuravel (Kharkov) and A. Ustinov (Karlsruhe) modulated laser resonator transmission laser OFF |S 21(f 0)|2 laser ON |S 21(f 0)|2 f 0 Pin f D|S 12|2 ~ [l JRF(x, y)]2 A dl co-planar resonator f 0 ~ 5. 2 GHz Local heating produces a change in transmission coefficient proportional to the local value of JRF 2 J. C. Culbertson, et al. J. Appl. Phys. 84, 2768 (1998) 28 Pout A. P. Zhuravel, et al. , Appl. Phys. Lett. 81, 4979 (2002)

2 -D Response Map for RF Current Distribution of a Sample Fundamental resonance mode (5. 2 GHz) 8. 5 mm 10 m. V RF photoresponse ~ Jrf 2(x, y) LAO 0 m. V T = 79. 5 K f = 5. 2133 GHz P = - 6 d. Bm 29 240 nm thick film

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Standing Wave JRF Pattern at Fundamental Frequency Photoresponse (a. u. ) f=5. 2133 GHz T=79. 5 K with 8672 A Generator P=-6 d. Bm in scale of 8672 A Fmod=99. 99 k. Hz Fit: kfit = 0. 39 mm-1 ktheory = 0. 42 mm-1 31 2 D image Proof that measured PR ~ JRF 2 to first order approx.