An Exact Quantum Theory of the Time-Dependent Harmonic Oscillator and of a Charged Particle in a Time-Dependent Electromagnetic Field
J. Math. Phys. 10, 1458 (1969); doi:10.1063/1.1664991
Issue Date: August 1969
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The theory of explicitly time-dependent invariants is developed for quantum systems whose Hamiltonians are explicitly time dependent. The central feature of the discussion is the derivation of a simple relation between eigenstates of such an invariant and solutions of the Schrödinger equation. As a specific well-posed application of the general theory, the case of a general Hamiltonian which settles into constant operators in the sufficiently remote past and future is treated and, in particular, the transition amplitude connecting any initial state in the remote past to any final state in the remote future is calculated in terms of eigenstates of the invariant. Two special physical systems are treated in detail: an arbitrarily time-dependent harmonic oscillator and a charged particle moving in the classical, axially symmetric electromagnetic field consisting of an arbitrarily time-dependent, uniform magnetic field, the associated induced electric field, and the electric field due to an arbitrarily time-dependent uniform charge distribution. A class of explicitly time-dependent invariants is derived for both of these systems, and the eigenvalues and eigenstates of the invariants are calculated explicitly by operator methods. The explicit connection between these eigenstates and solutions of the Schrödinger equation is also calculated. The results for the oscillator are used to obtain explicit formulas for the transition amplitude. The usual sudden and adiabatic approximations are deduced as limiting cases of the exact formulas.
©1969 The American Institute of Physics
| History: | Received 8 July 1968 |
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PUBLICATION DATA
0022-2488 (print)
1089-7658 (online)
REFERENCES (10)
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H. R. Lewis, Jr., J. Math. Phys. 9, 1976 (1968); [ISI]
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The two special systems that we consider in Secs. III and IV have been treated along different lines by M. Kolsrud: (a) “Exact Quantum Dynamical Solutions for Oscillator-Like Systems,” Institute for Theoretical Physics, University of Oslo (Norway), Institute Report No. 28 (1965);
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L. Landau, Z. Physik 64, 629 (1930).
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R. B. Dingle, Proc. Roy. Soc. (London) A211, 500 (1952).
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L. D. Landau and E. M. Lifshitz, Quantum Mechanics: Non-relativistic Theory (Addison-Wesley Publ. Co., Inc., Reading, Mass., 1965), 2nd. ed., p. 426. There is an error in this derivation: the wavefunction is assumed proportional to eim
, but the subsequent formulas are derived for e−im
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A method for expressing the general solution of Eq. (45) for arbitrary
(t) in terms of independent solutions of the equations for a classical oscillator has been described in Ref. 1. -
P. A. M. Dirac, The Principles of Quantum Mechanics (Clarendon Press, Oxford, 1947), 3rd ed.
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For the present we are omitting the time label t in our notation for these eigenstates. When it is required for clarity, we shall replace |s> by |s;t> to denote an eigenstate at time t.
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This derivation is closely related to a derivation of an analogous invariant for the corresponding classical system. The treatment of the classical system is given in H. R. Lewis, Jr., Phys. Rev. 172, 1313 (1968). [ISI]
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L. Infeld, Phys. Rev. 59, 737 (1941). [ISI]
(c) Phys. Rev. 104, 1186 (1956). [ISI]
(b) L. Infeld and T. E. Hull, Rev. Mod. Phys. 23, 21 (1951);
(c) A. Joseph, ibid. 39, 829 (1967); [ISI]
(d) C. A. Coulson and A. Joseph, ibid. 39, 838 (1967). [ISI]







