Radiation at the Nanoscale by Quantum Mechanics Thomas Prevenslik QED Radiations Discovery Bay, Hong Kong 1 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 Introduction Today, Plancks BB radiation based on a standing wave model (SWM) of photons in a 3D cavity gives the Stefan-Boltzmann (SB) equation for the far field radiative transfer between hot and cold surfaces QM = quantum mechanics Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012

2 Problem Based on the SWM, the SB equation in the near field is currently thought invalid because long wavelength SB radiation is excluded from the 1D gap between hot and cold surfaces But in this presentation, I argue: The SB equation is still valid in the near field. Argument is based on the QED induced conservation of excluded SB radiation by creating standing wave photons at the EM resonance given by TIR Simply put, the QED photons tunnel SB radiation across the gap QED = quantum electrodynamics TIR = total internal reflection EM = electromagnetic Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 3

Photon Tunneling Evanescent Waves Standing QED Photons SWM excludes tunneling of evanescent waves perpendicular waves gap QED Induced Radiation Standing QED Photons SWM excludes SB radiation .

But QED conserves excluded radiation by creating standing wave QED photons QED ~ EM energy in QM box creates photons QED could be invoked as the tunneling mechanism for excluded perpendicular evanescent waves, but then no need for evanescent tunneling Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 4 Outline Theory Nano Structures and Nano Cavities Heat capacity of the atom by classical physics and QM TIR Confinement of QED Photons

Applications Near Field Radiative Heat Transfer Flat Surfaces Sphere and Flat Surface 5 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 Theory 6 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 Nano Structures Refractive Index n of Nano Structures > that of the surroundings NPs by Rubbing Tribochemistry

Static electricity Joule Heat Thin Films Memristors Ovshinsky Effect 1/f Noise Nanostructure Light Laser/Supernovae Photons Molecular Collisions Nanofluids Biology

EM Radiation or Charge No Temperature change in conserving absorbed EM energy because by QM heat capacity vanishes 7 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 Nano Cavities Refractive Index n of Nano Cavities < that of the surroundings Voids Standing

QED Photons Gaps Standing QED Photons Excluded SB radiation is conserved by QED creating photons that tunnel across the gap 8 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 Heat Capacity of the Atom Classical Physics

5 QM hc E hc exp 1 kT

kT 0.0258 eV d<5 Nanoscale Wiens law at 300K gives peak BB radiation at ~ 10 microns E ~ kT/40 QSB for d < 5 microns is the same as for d = 5 microns Temperatures of surface atoms are at ambient, not at TH and TC Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 9 TIR Confinement Nano Structures: The high surface to volume ratio of Nano Structures creates QED photons by concentrating absorbed EM energy from inside the Nano Structure at the surface of the Nano Structure

Nano Cavities: QED photons are created as the EM energy from the outside surroundings is concentrated at the surface of the Nano Cavity. Nano Structures and Cavities: The QED photons created: f = (c/n)/ = 2d E = hf d = diameter EM energy concentrated in surface creates QED photons Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 10 Applications Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 11

Near-Field Heat Transfer Solution of Maxwells equations for Q by evanescent waves Observations Q diverges as d 0 Restricted to materials with imaginary permittivity (, T) = Frequency form of Einstein-Hopf evaluated for parallel evanescent waves in the NIR where the atom has some heat capacity FDT not explicitly included in Maxwell solution for atoms in gap surfaces that under EM confinement in the UV lack heat capacity FDT = Fluctuation Dissipation Theorem 12 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 Maxwell - QED Comparison At d = 50 nm, heat transfer by Maxwell exceeds SB by 3-4 orders of magnitude

that has led to optimism for high efficiency in near field heat transfer In contrast, QED does not increase heat transfer efficiency above SB QQED = QSB for all d, but energy E and number NP of QED photons varies Data from A. Narayanaswamy, et al., Breakdown of the Planck blackbody radiation law at nanoscale gaps, Appl Phys A (2009) 96: 357362 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 13 Flat Surfaces* PS Standing QED Photons The 1.6 micron (instead of 1 micron) gap necessary to find agreement between

Maxwell and experiment* suggests the actual heat is lower because QED radiation losses were not included in heat balance, as explained in the next slide for the sphere and flat surface PS *A. Narayanaswamy, et al., Breakdown of the Planck blackbody radiation law at nanoscale gaps, Appl Phys A (2009) 96: 357362 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 14 AFM Heat Sensor QED Radiation

Laser increases temperature of sphere, but some QED radiation lost to surroundings Au expands more than Si3N4 causing AFM cantilever to bend in proportion to laser power Au Si3N4 Standing QED Photons Laser = QM fraction absorbed P = Laser power K , A, L = AFM Conductivity, area, length M = Sphere mass

Co = QM Sphere heat capacity Co = Nominal heat capacity T, To = Temperature Steady state solution *S. Shen, et al., Thermal conductance of bimaterial microcantilevers, Appl Phys Lett. (2008) 92: 063509 Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 15 Sphere Absorption by QM* At Atlanta, 5 micron sphere was reported to give a reduced (heat transfer v gap) curve compared to that for a 50 micron sphere. The graph shows the QM fraction for 5 micron silicate sphere is reduced compared to a 50 micron sphere. For NPs, vanishes.

This is a QM effect that cannot be explained by classical physics. *E. Rousseau, et al., Radiative heat transfer a the nanoscale, Nature Photonics, (2009) 3: 514-7. Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 16 Conclusions QED radiation provides a simple alternative to Maxwells equations and avoids divergence problems and restriction of imaginary permittivity Excluded SB radiation between surfaces of Nano Cavities is conserved by creating standing QED photons. QED tunnels SB radiation across nanoscale gaps By QED radiation, Plancks limit on far field radiative heat transfer is not exceeded in the near field. QM negates assumption in Maxwell solutions that atoms in surfaces of nanoscale gaps have bulk temperatures

Why do Maxwells solutions for evanescent waves significantly differ from QED induced radiation based on QM? Question may be answered in this presentation. In 1900, Planck answered this question for BB radiation with QM instead of classical physics by EM waves that satisfy Maxwell's equations Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 17 Questions & Papers Email: [email protected] http://www.nanoqed.org Nanorad 2012: Int. Workshop Nano-Micro Thermal Radiation, Miyagi, May 23-25, 2012 18