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For alternative betydninger, se Superposition.

Kvantemekanisk superposition eller kvantefysisk superposition er et fundamentalt kvantemekanisk fænomen. Kvantemekanisk superposition er det, at et fysisk system (f.eks. en elektron) kan eksistere i mere end én af dets teoretisk mulige (egenskabskonfigurationer) samtidig; men, når målt/observeret, giver det kun én tilstand (som beskrevet i ).

Kvantemekanik

• • Historie

Baggrund
Bra-ket notation • • • Interferens • Klassisk mekanik

Grundlæggende koncepter
Atommodel • Bølgefunktion • CPT-teoremet • Bølgefunktionens kollaps • • • • • Måling • Sammenfiltring • Spin • Superposition • Tunnelering • Kvantespring • Kvanteteleportation • • Partikel-bølge-dualitet • Partikel i en boks • Paulis udelukkelsesprincip • • Ubestemthed • Virtuel partikel

Eksperimenter
Bells tests • Bose-Einstein-kondensat • Dobbeltspalte • • Kvante Hall-effekten • • Stern–Gerlach


Born-Oppenheimer • Hartree-Fock • • • • • •

Ligninger
Dirac • Klein–Gordon • • Rydberg • Schrödinger


• Københavnerfortolkningen • de Broglie–Bohm • • • Schrödingers kat

Avancerede emner
Dc-squid • Degenereret stof • Josephson-kontakt • Kvantecomputer • Kvanteelektrodynamik • Kvantefeltteori • • Kvantekemi • Kvantekromodynamik • Kvanteoptik • • • Kvanteø • Kvasipartikel • Rapid single flux quantum • Resonanstunneldiode • Resonanstunneltransistor • Single electron transistor • • Tunneldiode •

Videnskabsmænd
Bell • Bogoljubov • Bohm • Bohr • Born • Bose • de Broglie • Compton • Dirac • Debye • Ehrenfest • Einstein • Everett • Fock • Fermi • Feynman • Heisenberg • Hilbert • • • von Neumann • Pauli • Lamb • Laue • Planck • Raman • Rydberg • Schrödinger • Sommerfeld • Weyl • Wigner • Zeeman • Zeilinger

Matematisk svarer det til løsningsmulighederne til Schrödinger-ligningen; da Schrödinger-ligningen er lineær, vil enhver linearkombination af løsninger også være en løsning. Sådanne løsninger laves ofte ortogonale (dvs vektorerne er vinkelrette på hinanden), som en elektrons energiniveauer.

Et eksempel på en direkte observerbar effekt af superposition er interferenstoppe fra en elektronbølge i dobbeltspalte-eksperimentet.

Et makroskopisk eksempel på superposition er fysikerne Andrew Cleland og John Martinis lille 30 mikrometer lange metalpaddel, som både kan oscillere og stå næsten stille samtidigt.

Kilder/referencer

American Association for the Advancement of Science (2010, December 16). Science's breakthrough of the year: The first quantum machine. ScienceDaily Citat: "...They even managed to put the gadget in both states at once, so that it literally vibrated a little and a lot at the same time -- a bizarre phenomenon allowed by the weird rules of quantum mechanics..."
University of California, Santa Barbara (2010, March 18). Quantum mechanics demonstrated in motion of objects large enough to see with naked eye. ScienceDaily Citat: "...They were able to create a single phonon...While exchanging this energy, the qubit and resonator become "quantum entangled," such that measuring the qubit forces the mechanical resonator to "choose" the vibrational state in which it should remain...[]...In a related experiment, they placed the mechanical resonator in a quantum superposition, a state in which it simultaneously had zero and one quantum of excitation. This is the energetic equivalent of an object being in two places at the same time..."
17 March 2010, nature.com: Scientists supersize quantum mechanics Citat: "...it is possible for the same particle to be doing two contradictory things simultaneously...Next, the researchers put the quantum circuit into a superposition of 'push' and 'don't push', and connected it to the paddle. Through a series of careful measurements, they were able to show that the paddle was both vibrating and not vibrating simultaneously..."

[1] American Association for the Advancement of Science (2010, December 16). Science's breakthrough of the year: The first quantum machine. ScienceDaily Citat: "...They even managed to put the gadget in both states at once, so that it literally vibrated a little and a lot at the same time -- a bizarre phenomenon allowed by the weird rules of quantum mechanics..."

[2] University of California, Santa Barbara (2010, March 18). Quantum mechanics demonstrated in motion of objects large enough to see with naked eye. ScienceDaily Citat: "...They were able to create a single phonon...While exchanging this energy, the qubit and resonator become "quantum entangled," such that measuring the qubit forces the mechanical resonator to "choose" the vibrational state in which it should remain...[]...In a related experiment, they placed the mechanical resonator in a quantum superposition, a state in which it simultaneously had zero and one quantum of excitation. This is the energetic equivalent of an object being in two places at the same time..."

[3] 17 March 2010, nature.com: Scientists supersize quantum mechanics Citat: "...it is possible for the same particle to be doing two contradictory things simultaneously...Next, the researchers put the quantum circuit into a superposition of 'push' and 'don't push', and connected it to the paddle. Through a series of careful measurements, they were able to show that the paddle was both vibrating and not vibrating simultaneously..."