Quantum studies in LIGO Lab

Quantum activities in LIGO Lab Injection of squeezed states Demonstration on 40m prototype Showed 2.9 dB (40%) improvement in SNR Goda et al., Nature Phys. 4, 472 (2008) Proposed implementation on H1 Under consideration by review committee Sigg et al., LIGO-T070265-C-D Optical cooling and trapping of mirrors All-optical trap for a 1 gram mirror Minimum effective temperature of 0.8 K Corbitt et al., Phys. Rev. Lett. 98, 150802 (2007) Optical dilution and cooling of a 1 gram mirror Minimum effective temperature under 7 mK Corbitt et al., Phys. Rev. Lett. 99, 160801 (2007) Active feedback cooling of the kilogram-scale LIGO mirrors Minimum effective temperature of 1.4 mK LIGO Scientific Collaboration, in preparation

Quantum-enhanced interferometry Squeezed state injection

Squeezing injection in 40m prototype Laser Prototype GW detector SHG Faraday isolator The squeeze source drawn is an OPO squeezer, but it could be any other squeeze source, e.g. ponderomotive squeezer. OPO Homodyne Detector Squeeze Source GW Signal

Quantum enhancement 2.9 dB or 1.4x K. Goda, O. Miyakawa, E. E. Mikhailov, S. Saraf, R. Adhikari, K.McKenzie, R. Ward, S. Vass, A. J. Weinstein, and N. Mavalvala, Nature Physics 4, 472 (2008)

Proposed squeeze injection test in Enhanced LIGO circa 2010 Post-S6, pre-AdLIGO Test performance of squeezer at ELIGO noise level Improve SNR in shot-noise-limited band Do no harm in other bands Important step for readiness of squeezer for AdLIGO Improve SNR and/or Operate at lower power for same sensitivity

Advanced LIGO with squeeze injection Radiation pressure Shot noise

Mechanical oscillators in the quantum regime Trapping and cooling mirrors

Reaching the quantum limit in mechanical oscillators The goal is to measure non-classical effects with large objects like the (kilo)gram-scale mirrors The main challenge  thermally driven mechanical fluctuations Need to freeze out thermal fluctuations Zero-point fluctuations remain One measure of quantumness is the thermal occupation number Want N  1 Colder oscillator Stiffer oscillator

Cooling using optical forces Mechanical forces introduce thermal noise Optical (or other ‘cold’) forces needed Optical trapping and cooling Radiation pressure of a detuned cavity provides restoring and damping forces Restoring force  trap Damping force  cool Key ingredients Light, movable mirrors High laser power Low noise performance to ensure mirror responds primarily to radiation pressure

Experimental cavity setup 10% 90% 5 W Optical fibers 1 gram mirror Coil/magnet pairs for actuation (x5)‏

An all-optical trap for a 1 gram mirror Stiffer than diamond Increasing subcarrier detuning Stable Optical Spring T. Corbitt, Y. Chen, E. Innerhofer, H. Müller-Ebhardt, D. Ottaway, H. Rehbein, D. Sigg, S. Whitcomb, C. Wipf and N. Mavalvala, Phys. Rev. Lett 98, 150802 (2007)

Cooling the kilogram scale mirrors of Initial LIGO Teff = 1.4 mK N = 234 T0/Teff = 2 x 108 Mr ~ 2.7 kg ~ 1026 atoms Wosc = 2 p x 0.7 Hz LIGO Scientific Collaboration

Activities of the LAAC

LIGO Academic Advisory Council The LIGO Academic Advisory Council is charged with advising the LIGO Executive Director and Directorate on issues related to education of all students and post-docs who are participating in LIGO and to provide oversight of the quality of the education they receive through their participation in LIGO Formed in Spring 2006 Committee Nergis Mavalvala, MIT (Chair) Rana Adhikari, Caltech Nelson Christenson, Carleton College Ex-officio members Jay Marx, Caltech Albert Lazzarini, Caltech Dave Reitze, University of Florida Student/post-doc liaisons Evan Goetz, U. Michigan Sam Waldman, Caltech

LAAC activities Maintain web site and wiki Provide online educational resources Thorne’s famous Ph207 lectures Weinstein’s REU lecture series for undergraduates Buonanno’s SLAC summer school lecture series Links to LIGO document center Links to workshops and summer schools and seminar series And much more… Administer LIGO fellowship for outstanding students to spend one year at a LIGO Observatory Annual competition leading to two fellowships Supplemental stipend ($5000) Travel funds Maintain database of graduate students within the LSC Student thesis topics maintained by faculty advisors Individual student wikis maintained by each student Host annual town hall style meeting for students and postdocs

Recent “graduates” Doctoral students Masters students Postdocs Joseph Betzweiser (2007) postdoc at Caltech Thomas Corbitt (2008) postdoc at MIT Keisuke Goda (2007) postdoc at UCLA Lisa Goggin (2008) postdoc at UWM Masters students Brett Shapiro (2007) Gautier Brunet (2007) A. Stochino* (2007) I. Taurasi* (2007) Postdocs Rana Adhikari faculty at Caltech Duncan Brown faculty at Syracuse Univ. Vuk Mandic faculty at U. Minnesota Peter Shawhan faculty at U. Maryland Sam Waldman staff scientist at MIT Several undergraduate theses * Degree granting institution not Caltech or MIT