Landau levels - 2025 ACF Winter

Question

Without boundary conditions, the wavefunction for the lowest of these states consists of a Gaussian times an arbitrary analytic function. For 10 points each:

[10h] Name these quantized cyclotron orbits for electrons in a magnetic field. The derivation of these states shows they are analogous to quantum harmonic oscillators with energy proportional to field strength.

ANSWER: Landau levels

[10m] The filling of Landau levels helps explain the integer version of this effect, which was discovered by Klaus von Klitzing in 1980. In this effect, the conductance of a system in a strong magnetic field is quantized in units of e-squared over h.

ANSWER: quantum Hall effect [accept integer quantum Hall effect; accept fractional quantum Hall effect; prompt on Hall effect]

[10e] Landau levels and the quantum Hall effect are only observed in systems of this type. Systems with this property are completely confined to a surface.

ANSWER: two-dimensional [or 2D]

<Editors, Physics>

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Summary


Florida	Main	Y	13	5.38	23%	31%	0%
North	Main	Y	10	7.00	40%	30%	0%
Overflow	Main	Y	3	3.33	0%	33%	0%
Pacific Northwest	Main	Y	10	9.00	40%	30%	20%
Southeast	Main	Y	11	10.00	36%	55%	9%
Upper Mid-Atlantic	Main	Y	8	8.75	25%	50%	13%
Upstate NY	Main	Y	8	6.25	25%	38%	0%
2025 ACF Nationals	2025-08-09	Y	14	10.71	43%	57%	7%

Data


McGill A	Guelph A	0	10	0	10
McMaster C	Queen's A	0	0	10	10
McMaster B	Queen's B	0	0	0	0
Toronto A	Toronto B	0	10	10	20
Toronto C	McMaster A	0	10	0	10
Ottawa	Toronto D	0	0	0	0
Toronto E	Western Ontario	0	0	10	10
Toronto G	Toronto F	0	0	0	0
Toronto H	Carleton	0	0	0	0
McGill C	Toronto I	0	10	0	10
Toronto Metropolitan	Toronto J	0	0	0	0
Toronto K	McGill B	0	0	0	0
Waterloo	Guelph B	0	0	0	0
George Mason A	Penn A	0	10	10	20
George Washington A	Catholic University	0	0	0	0
George Washington B	Maryland C	0	0	0	0
Maryland D	Johns Hopkins B	0	0	10	10
Johns Hopkins A	Maryland A	0	10	10	20
Georgetown B	Maryland B	0	0	0	0
NYU B	Notre Dame E	0	10	0	10
Georgetown A	Penn B	0	0	10	10
UMBC A	Johns Hopkins C	0	0	0	0
George Mason B	VCU A	0	0	0	0
Missouri A	SIUE	0	10	0	10
WashU B	Truman State	0	0	0	0
William Woods	WashU D	0	0	0	0
Chicago A	Notre Dame D	10	10	10	30
Indiana A	UIC	10	10	10	30
Michigan B	Indiana B	0	0	0	0
Michigan C	Chicago B	0	0	0	0
Michigan A	Purdue B	0	10	10	20
Notre Dame B	Purdue C	0	0	0	0
Louisville B	Illinois A	0	0	0	0
Louisville A	Illinois C	0	0	0	0
Kentucky	Michigan D	0	0	0	0
Notre Dame A	Chicago D	0	0	10	10
BU	MIT B	10	10	10	30
BC B	Bowdoin B	0	0	0	0
Brown C	Brandeis Clemenceau	0	0	0	0
Brown B	Brandeis Lloyd George	0	0	0	0
Brandeis Orlando	Brandeis Wilson	0	0	0	0
MIT A	Amherst A	0	10	10	20
Tufts A	Tufts B	0	10	10	20
Yale B	BC A	0	0	0	0
Northwestern A	Alberta B	0	10	0	10
Arizona State A	Texas A	0	10	10	20
Texas B	McGill D	0	0	0	0
UTD A	Iowa	10	10	10	30
Cornell-UG	Dartmouth	0	10	10	20
Brown A	Harvard	0	10	0	10
Yale A	Williams	0	10	0	10
Ohio	Arizona State B	0	0	0	0
Rose State	Northwestern C	0	0	0	0
Tulsa	UTD B	0	0	0	0
UCO	Northwestern B	0	10	0	10
Alabama A	Alabama B	0	0	0	0
Huntsville A	Auburn B	0	10	0	10
Bruin A	Auburn A	0	10	0	10
Georgia Tech C	Georgia Tech A	0	0	0	0
Georgia Tech B	Vanderbilt B	0	0	10	10
Georgia Tech D	Vanderbilt A	0	10	10	20
Huntsville B	Sewanee A	0	0	0	0
Mississippi State A	UAB A	0	0	0	0
Imperial B	Bristol B	0	10	10	20
Sheffield B	City St George's A	10	0	0	10
Durham B	Imperial C	0	0	0	0
Edinburgh B	Cambridge A	0	0	10	10
Birmingham A	Imperial A	0	10	0	10
Edinburgh A	LSE A	0	0	0	0
Lancaster A	Cambridge C	0	10	0	10
LSE B	Manchester B	0	0	0	0
Oxford A	Manchester A	0	10	0	10
Oxford B	Durham A	0	10	0	10
Southampton A	Sheffield C	0	10	10	20
Cambridge D	Southampton B	0	10	10	20
Warwick A	Sheffield A	0	0	10	10
Bristol A	Warwick B	0	10	10	20