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Symphony of Imaginary Frequencies: Quantum Decay of the Inverted Well

Original: "Quantum mechanics of inverted potential well -- Hermitian Hamiltonian with imaginary eigenvalues, quantum-classical correspondence"
· Ni Liu, J. -Q. Liang
arXiv:2505.00475v2 · 2025-05-01 · CC BY · ⏱ 1 min · Quantum Physics
In an inverted well, energy becomes purely imaginary, and the quantum state devolves into rapid decay — only a duet of dual worlds restores harmony.
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A particle on a perfectly sharp peak inevitably falls — in the quantum world, the uncertainty principle itself pushes it. But it turns out this decay can be heard as a note at an imaginary frequency. Coherent states play a classical melody, though each individual note is an explosion or a fade-out. The duet of dual worlds opens the door to a new understanding of the arrow of time and, perhaps, to controlling quantum decay.

🎯 The ground state of the inverted well is 'omnipresent': the particle is smeared along the entire axis with constant probability density and a subtle interplay of phases. To normalize such a state, Feynman summoned the aid of an imaginary measure — a mathematical curiosity from his arsenal.

🎬 The instability of the inverted well resembles the problem of wormholes from science fiction: they too tend to collapse without exotic matter. In our case, the stabilizing role is played by dual bra-states — quantum 'exotic matter' that maintains balance.

E_n = i\hbar\omega (n + \tfrac{1}{2})
Purely imaginary energies proportional to the level number; the imaginary part determines the decay rate.
\Delta x \Delta p = \frac{1}{2}
The product of uncertainties saturates the Heisenberg inequality, just as for an ordinary harmonic oscillator.
Scientists
Alan GuthAndrei LindeGeorges LemaîtreJames PeeblesNiels BohrPascual Jordan
Tags
uncertainty principle quantum optics quantum decoherence quantum measurement Quantum Field superposition Bose-Einstein condensate quantum information inflation
Laws
Friedmann equationsHeisenberg uncertainty principleNoether's theoremsuperposition principlespin–statistics theoremFermi's golden rule
Original: arXiv:2505.00475v2 · CC BY · bridge42worlds