m = mass of the particle E =

Transcription

1 Kumpula The basic ideas of quantum physics Quantum mechanics makes nano diffeent Risto Nieminen COMP/Applied Physics Aalto Univesity School of Science and Technology 1. Matte has both wave- and paticle-like popeties. - Wavelength λ = h 2mE h = Planck s constant 34 Js m = mass of the paticle E = its kinetic enegy

2 In themal equilibium, 23 1 k B = JK E = 3 2 Quantum mechanics is impotant when a = k B T Boltzmann s constant 19 J = ev 300 K = 25,8 mev λ intepaticle spacing o device size. Fo electons, nealy always. Fo potons, sometimes (especially at low tempeatues). Fo He atoms, at vey low tempeatues Fo othe atoms, at even lowe tempeatues (e.g. cold atomic gases, BEC) Inside nuclei and nucleons: diffeent length and enegy scales! a Electon Wave Intefeence Expeimental EVIDENCE Whethe it is light, o electons, the Double Slit Diffaction expeiment shows that in BOTH cases intefeence effects occu! What about in the opposite case? Is light made up of paticles? The expeimental evidence says YES! This is Einstein s photoelectic effect. 1 ( mv 2 2 ) max = hf φ

3 Wave-like popeties: Diffaction Scatteing Uncetainty pinciple Coheence Quantum confinement, zeo-point enegy Paticle-like popeties: Single-paticle counting Scatteing Ballistic tanspot The Bizae Wold of Quantum UNCERTAINTY The quantum wold is pobabilistic. This is decibed by Heisenbeg s Uncetainty Pinciple. The uncetainty elations ae: Δ x Δ p h 2 Δ E Δ t h 2 Notice that the uncetainty pinciple is unimpotant to macoscopic objects since Planck's constant, h, is so small (of ode ). Fo example, the uncetainty in position of a thown baseball is millimetes!

4 QUANTUM WORLD weid = counteintuitive : wave-paticle dualism inheently paallel quantum computing phase infomation many-paticle symmety/antisymmety mathematical desciption of electons vey complex ( femion sign poblem ) coupling to (classical) envionments decoheence dissipation

5 E min = Quantum confinement h π ml Enegy E min L

6

7 2. Moe quantum popeties Paticles (e.g. electons) have intenal degees of feedom : Spin Magnetism Many physical popeties ae quantized, i.e. only discete values ae possible, e.g. - Enegy levels specta (tansitions between enegy levels) - Angula momentum - Conductivity -Magneticflux - Voticity (in quantum liquids) - etc. The popeties of of the quantum paticles ae descibed by the Schödinge equation ( wave equation ) the wave function ψ (, t) The wave function descibing seveal paticles is eithe symmetic o antisymmetic with espect to paticle exchange quantum statistics, femions (such as electons) and bosons (such as photons (light quanta) o some light atoms)

8 The wave function can be intepeted as the pobability of finding the system (o an obsevable) in a given state. Fo example, the electon density 2 ), ( ), ( t t n ψ = ), ( ), ( ), ( t t H dt t d i h ψ ψ = Time evolution: Hamilton opeato: ), ( t V m H h + = Schödinge wave equation + bounday conditions Stationay eigenstates ) n ( ψ Geneal state is a supeposition of the eigenstates ) ( ) ( ), ( t c t n n n ψ ψ = Quantum infomation and computing

9 Quantum physics can be completely maied with special elativity: quantum electodynamics (QED). Not with geneal elativity (gavity), but the enegy scale is lage by a facto of Standad model : QED + quantum chomodynamics (QCD). Challenge: many inteacting paticles - collective popeties (e.g. feomagnetism) - emegent phenomena (e.g. supeconductivity) - macoscopic quantum effects (e.g. supefluidity) Coulomb inteaction

10 Playing with Atomic Lego But I am not afaid to conside the final question as to whethe, ultimately in the geat futue we can aange the atoms the way we want; the vey atoms,, all the way down! All things ae made of atoms. Electons ae the glue. - Richad P. Feynman, Linus Pauling, 1962 RICHARD FEYNMAN CONDENSED MATTER PHYSICS AND CHEMISTRY

11 NANOSCIENCE: Thee Is Plenty of Room at the Bottom Cental paadigms fo Condensed Matte Physics Weakly inteacting electons Stongly inteacting electons Richad P. Feynman Decembe 1959 Femi-Landau theoy Quasipaticles Band theoy Spin fluctuations Mixed-valence behavio Andeson and Kondo esonances How do we wite small? Infomation on a small scale Bette electon micoscopes The mavellous biological system Miniatuizing the compute Miniatuization by evapoation Poblems of lubication A hunded tiny hands Reaanging the atoms Atoms in a small wold 10-9 m BCS supeconductivity Exotic supeconductivity Disode-induced localization Wigne cystallization Intege QHE Factional QHE Fantastic testbed fo many-body phenomena: cold atoms in optical lattices.

12 Cental paadigms fo CMP (contd.) Cental paadigms fo CMP (contd.) Inteacting atoms Reductionist appoach: Quantum mechanics and electomagnetic inteactions Elementay excitations Emegence: phonons, plasmons, magnons, spinons etc. Response functions Gound state Stuctue-popety elationships Phase stability and tansitions Dynamics and excitations Spectoscopy Reactions Fom chemical bonds to bands Collective phenomena Equilbium tanspot Non-equilibium and dissipation Density-functional theoies Multiscale models Entanglement and decoheence These two paadigms can be linked.

13 Designing with Conventional ATOMS Atomic clustes have supising popeties at the nanoscale! To undestand the chemical bond, we need the machiney of quantum physics. Electons ae the glue. They behave quantum-mechanically and give ise to the vaiety of chemical bonds: -The ionicbond - The covalent bond - The metallic bond - The hydogen bond - The van de Waals bond Single phosphous atoms implanted into a silicon substate.

14 Small is diffeent: Non-scalable size egion the nanoscale mateials and stuctues have new, functional popeties Popety N α no. of atoms/molecules N

15 NANOSCIENCE AND TECHNOLOGY: HANDSHAKING OF The thee pillas of nanoscience and -technology quantum and classical phenomena equilibium and non-equilibium phenomena top-down and bottom-up appoaches eductionist and emegent viewpoints ( moe is diffeent ) Manufactue and manipulation top-down : lithogaphy bottom-up : self-assembly Chaacteisation, imaging and pobing SPM TEM PES Theoy, modelling and simulation Pedictive computation of physical, chemical and biological functions Pocess design Intepetation of pobe data Computational nanoscience

16 mako - mm TOP-DOWN Novel Nanosystems miko - μm nano - nm poikkitieteellinen ja -teknologinen nanotutkimus takkuusmanipulointi mikoelektoniikka litogafia etsaus kasvatus BOTTOM-UP itseoganisoituvuus kemiallinen synteesi molekyylisuunnittelu SPM-manipulointi Magnetic multilayes : Giant Magnetoesistance

17 Exotic Quantum Systems WELCOME TO THEWORLD OF ARTIFICIAL ATOMS! QUANTUM DOTS! FULLY TUNABLE SOLID STATE DEVICES Electons confined in a vey small space by an electostatic potential. CONFINEMENT = ATOM-LIKE PROPERTIES B Quantum Rings and things... Have vey stange quantum popeties, such as pesistent cuents, when a magnetic field is applied. Also inteesting magnetism which may be applied in computing.

18 Atoms tapped in Optical Lattices Atoms tapped in optical potentials. The optical potentials can be changed and theefoe the atificial atomic stuctue can also be changed. This gives us geate design feedom to ceate new nanoscale devices, beyond that which we could get fom the peiodic table elements.

19

20 Atomic Foce Micoscopy: Tip Change Imaging F - t Tip Change Imaging Ca 2+

21 Biowold is also a nanowold. Electophoesis of nanocolloids Lipid membanes

22 Quantum dots in biology: changing colous Quantum physics in biology: olfaction The biggest thing we can smell is atoms lage. Shape does not solve it: lock and key not enough. Feocene vs. nickeloscene: exactly the same stuctue, smell vey diffeent! Explanation: inelastic electon tunnelling fom the molecules. Othe examples: poton tansfe concentation gadient of potons acoss cell membanes

23 Quantum wies: the quantization of conductivity Au quantum wie, STM Quantum of conductance: G 0 = 2e 2 /h = 1/12.9 kw, elongation foce oscillations C 60 (fulleene) on a metal suface The mophology of Pt suface M.R. Soensen et al., Phys. Rev. B. 57, 3283 (1998) G. Rubio, N. Agaït, and S. Vieia, Phys. Rev. Lett. 76, 2302 (1996) Gaphite suface Tiblock-copolyme

24 Mooe s Law Godon Mooe Founde of Intel Inc. Electonics Magazine, 1965 Nanoelectonics and spintonics as a new platfom fo infomation technology: a possibility to extend Mooe s Law into the futue. The numbe of switches on a silicon chips will double evey 12 months (late evised to 18 months)

25 The shinking featue size One needs new insulato mateials HfO 2 90 nm pocess capacitance 1 leakage cuent 1 capacitance 1.6 leakage cuent < 0.01

26 Cabon nanotube as a quantum wie Single-electon tansisto Etching of silicon sufaces (Miguel Gosalvez) Nanoscale Au clustes ae eactive!

27 Mono-laye Potected Gold Nanoclustes Rautaoksidi-nanopatikkeli Univ. Califonia Bekeley PbSe-kvanttipiste elektonimikoskopia

28 Metallinen, yksiseinäinen hiilinanoputki (SWNCT) ultamikoskopia : - alle 0.1 nanometin takkuus a) elektonidiffaktiokuva kieteisyys b) tansmissioelektonimikoskopia Aalto/Uusien Mateiaalien Keskus (Esko Kauppinen) α = d = 2.07 nm Kaksosaja <110>-suunnassa STiO 3 -peovskiitissa ( m, n ) = (21, 9) d (21,9) = 2.09 nm α (21,9) = 17.0

29 Nobel 2010: Gaphene One atomic laye of hexagonal cabon

30 Samsung Electonics