Page 7 - GALIET PHYSICS BLOSSOMS IV+

1.1: Superpositions can be most easily discussed in terms of the 2-slit experiment.
1.1(a): describe the 2-slit experiment for a set of quantum ’particles’ like photons or electrons. Discuss in particular what will be seen when (i) one slit is open, (ii) when 2 slits ore open, and (iii) when one lowers the rate at which particles go through the slits so that only one is going through at any one time. 1.1(b): what would be seen under the same circumstances if the electrons or photons behaved classically.
TWO SLITS OPEN
ONE SLIT OPEN
CLASSICAL
(One Definite State System)
QUANTUM (Simultaneous State System)
CLASSICAL
(One Definite State System)
QUANTUM (Simultaneous State System)
Particles show:
No interferenceàall arrive in bits at definite places.
We see the sum of each slit! We see more particles arriving at the center and decreasing little by little as they move away from the centre. (Please see page 4 for details and Figure).
Particles show:
No interferenceàall arrive in bits at definite places.
The particle can travel any of the paths through the slits.
Because the particle travels along the paths like a wave, the paths that each slit emits are like a wave.
When all of these possible paths are summed, it appears as if the particle were going through both slits simultaneously.1
As a result, we witness wave interference
Particles show:
No interferenceàall arrive in bits at definite places.
Please see page 4 for details as to what happens when either Slit 1 or Slit 2 is open.
Particles show:
No Interferenceàall arrive in bits at definite places on the screen.
1 Dr. Stamp. From class lecture notes, and from Basic Ideas of Quantum Mechanics. I. Quantum States. 18. •7•