Generation of squeezed phonon states by optical excitation of a quantum dot

Reiter, Doris E.; Sauer, Steffen; Huneke, Jan; Papenkort, Thomas; Kuhn, Thomas; Vagov, Alexei; Axt, Vollrath M.

doi:10.1088/1742-6596/193/1/012121

Cited by 2 publications

(1 citation statement)

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“…[5]) find applications in the fields of quantum communication [6] and gravitational wave detection [7,8]. A variety of squeezed states has been proposed for other bosons, in particular, those associated with atomic vibrations in quantum dots [9,10], quantum wells [11,12], molecules [13,14], and polaritons [15,16]. In crystals, the excitation and measurement of squeezed phonons can be of great importance for fundamental explorations and for studying the ultrafast dynamics of excited states on atomic length scales [17,18].…”

Section: Introductionmentioning

confidence: 99%

Transient phonon vacuum squeezing due to femtosecond-laser-induced bond hardening

et al. 2014

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Ultrashort optical pulses can be used both to create fundamental quasiparticles in crystals and to change their properties. In noble metals, femtosecond lasers induce bond hardening, but little is known about its origin and consequences. Here we simulate ultrafast laser excitation of silver at high fluences. We compute laser-excited potential-energy surfaces by all-electron ab initio theory and analyze the resulting quantum lattice dynamics. We also consider incoherent lattice heating due to electron-phonon interactions using the generalized two-temperature model. We find phonon hardening, which we attribute to the excitation of s electrons. We demonstrate that this may result in phonon vacuum squeezed states with an optimal squeezing factor of ∼0.001 at the L-point longitudinal mode. This finding implies that ultrafast laser-induced bond hardening may be used as a tool to manipulate the quantum state of opaque materials, where, so far, the squeezing of phonons below the zero-point motion has only been realized in transparent crystals by a different mechanism. On the basis of our finding, we further propose a method for directly measuring bond hardening.

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