Linear and Pump-Probe applications of THz Spectroscopy: The case of Elettra, Bessy-II, and SPARC S. Lupi Dipartimento di Fisica, INFN-University of Rome La Sapienza, and Italy SISSI Synchrotron Infrared Source for Spectroscopy and Imaging

Outline THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; High-Power/Sub-ps THz

Outline THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; High-Power/Sub-ps THz

THz Coherent radiation production from III Generation Machines: Bessy-II and Elettra Emission in the FIR/THz range is drastically enhanced. reference orbit: L = 240 m LL bunch,  p momentum compaction factor:  p/p  =  L/L Bessy-II IRIS Beamline U. Schade et al, PRL 2003 A. Perucchi et al,IP&T 2007 ELETTRA SISSI Beamline CSR Gl Take Home Message III Generation Machines High Rep Rate: 500 MHz Low-Energy per pulse: pJ Several ps bunch length Needed to compress the bunch  Special Operation Mode Linear THz Spectroscopy

Outline THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; High-Power/Sub-ps THz

Superconductivity today: THz spectroscopy plays a fundamental role

... because Superconductivity is ruled by low-energy electrodynamics: Superconducting gap : THz range Spectral weight of condensate and penetration depth: THz Mediators of pairing (phonons, etc.): THz Range of sum rules: THz, Mid, or Near Infrared Free-carrier conductivity above T c : Infrared

Basic optics of Superconductors Superconducting gap observed if: -sample in the dirty-limit (2  <  ) -Cooper pairs in s-wave symmetry ∫ [   , T>Tc) -   , T =c/  ps Ferrel-Glover-Tinkham Rule Drude absorption Drude reflectance  22 Minimum excitation energy: Cooper-pair breaking 2 

Superconductivity in Boron doped Diamond Oppenheimer Diamond carats Takenouchi-Kawarada-Takano Diamond 0.7 carats

B-Diamond: a text book example of BCS superconductivity s-wave Dirty-Limit Regime; 2  (0)=12±1 cm -1  2  /k B T C =3.2 ± 0.5  ≤  (T) : R n (  ) = 1 - [8  (T)/  p 2 ] 1/2  ≤ 2  (T) : R s (  ) = 1 Peak at 2  in Rs/Rn M. Ortolani et al, PRL, 2006

Mott-Hubbard Insulator to Metal Transitions Filling-Controlled MIT: static (doping) Bandwidth-Controlled MIT: static ( pressure) U Coulomb repulsion t Bandwidth

Mott-Hubbard Insulator to Metal Transition E. Arcangeletti et al, PRL (2007) VO 2 Pressure (Bandwidth) controlled MIT V2O3V2O3

Outline THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; High-Power/Sub-ps THz

Breaking Cooper Pairs Dynamically Photoionization For hω>2Δ light breaks Cooper pairs 1)Optical Pump - Optical Probe (THz Probe) hω>>2Δ  Recombination Dynamics affected by excess phonons 2) THz Pump – THz Probe hω THz ≥2Δ  Intrinsic dynamics Alternative processes if hω<2Δ Δ=Δ(J, B) at fixed T<Tc The high E (~MV) THz field may induce currents exceeding the critical current (breaking the Superconducting State with an Electric Field) The high B (~1 T) THz field may be larger that Bc (breaking the Superconducting State with a magnetic Field)

THz controlled Mott-Hubbard MIT THz pulses in the MV/cm range can drive lattice displacements in the pm range Filling-Controlled MIT: static (Doping) Dynamic (Phoexcitation) Bandwidth-Controlled MIT: static ( Pressure) dynamic (Radiation) U Coulomb repulsion t Bandwidth Dynamical modulation of U through intramolecular pumping

Outline THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials; THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra; Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials; High-Power/Sub-ps THz

Acceleration section Ondulator Section THz Section Laser Free Electron Laser Beam energy 155–200 MeV Bunch charge 1 nC Rep. rate 10 Hz Peak current 100 A  n 2 mm-mrad  n (slice) 1 mm-mrad   0.2% Bunch length (FWHM) 10 ps-100 fs

Transition Radiation occurs when an electron crosses the boundary between two different media Intensity is 0 on axis and peaked at  Polarization is radial CTR-THz Radiation

Velocity Bunching: Bunch length versus injection phase If the beam injected in a long accelerating structure at the crossing field phase and it is slightly slower than the phase velocity of the RF wave, it will slip back to phases where the field is accelerating, but at the same time it will be chirped and compressed ps/mm  t = 160 fs Velocity Bunching ps/mm  t = ps Time

CTR-THz emission 500 fs, 250 pC 300 fs, 500 pC 2 ps E. Chiadroni et al., J.Phys E. Chiadroni et al. APL 2012 S Lupi et al., J. Phys 2012 M. Ferrario et al., NIM A 2011

CTR measured emission from LINACs Electron beam energy Charge  t (bandwidth) THz pulse energy E-field Brookhaven (1) 120 MeV~ 1 nC- (2 THz) ≈100  J MV/cm SPARC (2) 120 MeV500 pC120 fs (10 THz) ≈100  J MV/cm FLASH (3) 1.2 GeV600 pC- (4 THz) >100  J MV/cm LCLS (4) 14.5 GeV350 pC50 fs (40 THz) 140  J >20 MV/cm (1) Y. Shen et al., Phys. Rev. Lett. 99, (2007) (2) E. Chiadroni, et al., APL 2012 (3) M.C. Hoffmann et al., Optics Letters 36, 4473 (2011) (4) D. Daranciang et al., Appl. Phys. Lett. 99, (2011)

Perspectives Increase machine energy  increase of bunch-charge (1 nC); Tailoring the electronic bunch shape  extended spectral coverage (20 THz); Narrow band THz radiation  Smith-Purcell Radiation:

Narrow-band and Tunable THz Radiation

Acknowledgments A. Perucchi E. Karanzoulis (ELETTRA) U. Schade E.Chiadroni and M. Ferrario (LFN-INFN): TERASPARC project Thank for your attention