1. Introduction to Nanomechanics (Spring 2012) Martino Poggio

2. Nanomechanical Measurements Displacement measurement is crucial for force transduction Different types of nanomechanical displacement measurements (advantages & disadvantages) Focus on optical interferometry Signal-to-noise ratio 04.04.2012Introduction to Nanomechanics2

3. Transduction vs. Sensing A transducer receives energy from one system and transmits it to another, often in a different form. A sensor responds to physical stimuli (e.g. heat, light, pressure, or motion) and generates an electronic signal for detection. Introduction to Nanomechanics304.04.2012

4. Mechanical Force Transducers Introduction to Nanomechanics4 x F Now we require a sensor for mechanical motion. 04.04.2012

5. Sensors for Mechanical Motion Tunneling Optical Deflection Optical Interferometry Microwave Interferometry Magnetomotive Piezoelectric Capacitive Introduction to Nanomechanics504.04.2012

6. Displacement Measurements Introduction to Nanomechanics6 STM Detection 04.04.2012

7. Displacement Measurements Introduction to Nanomechanics7 Laser deflection 04.04.2012

8. Displacement Measurements Introduction to Nanomechanics8 Fixed mirror “Movable” mirror “spring” x P in Laser interferometry 04.04.2012

9. Displacement Measurements Introduction to Nanomechanics9 Laser interferometry 04.04.2012

10. Displacement Measurements Introduction to Nanomechanics10 LIGO – Gravitational Wave Detection Laser interferometry 04.04.2012

11. Displacement Measurements Introduction to Nanomechanics11 Laser interferometry 04.04.2012

12. Displacement Measurements Introduction to Nanomechanics12 K. L. Lehnert, JILA Microwave interferometry – capacitive detection 04.04.2012

13. Displacement Measurements Introduction to Nanomechanics13 K. L. Lehnert, JILA 04.04.2012

14. Introduction to Nanomechanics14 Displacement Measurements Magnetomotive detection (via Faraday’s Law) A. Cleland & M. Roukes, 1999. Figure from K.L. Ekinci, Boston U. 04.04.2012

15. Introduction to Nanomechanics15 Displacement Measurements Capacitive detection 04.04.2012

16. Introduction to Nanomechanics16 Displacement Measurements Capacitive detection 04.04.2012

17. Introduction to Nanomechanics17 Displacement Measurements Piezoelectric detection 04.04.2012

18. Introduction to Nanomechanics18 Displacement Measurements Capacitive detection 04.04.2012

19. 13.10.2009Introduction to Nanomechanics19 QPC L R 2DEG e-e- QPC as a mechanical displacement detector

20. Introduction to Nanomechanics20 Spectral Density (A 2 / Hz)Spectral Density (Å 2 / Hz) 4.50 10 -25 10 -24 10 -23 10 -22 4.755.005.25 10 -21 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 Frequency (kHz) 10 -12 m / (Hz) 1/2 Displacement Measurements Measurement of Cantilever Thermal Noise at 4.2 K 04.04.2012