Vacuum Squeezing of Solids: Macroscopic Quantum States Driven by Light Pulses

Garrett, Gregory A.; Rojo, A. G.; Sood, A. K.; Whitaker, J.F.; Merlín, R.

doi:10.1126/science.275.5306.1638

Cited by 175 publications

(194 citation statements)

References 12 publications

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“…This behavior is associated with squeezed phonon states. At T 0 K this is to first order in j ii the result obtained by Garret et al [4,5]. Here, we focus on the consequences of Eq.…”

Section: (Received 15 November 1999)supporting

confidence: 62%

“…The data are dominated by an oscillation with 3.39 THz which matches the overtone of the TA phonon at the zone boundary. It is associated with the generation of squeezed phonon states as shown by Garret et al [4,5,9]. All higher frequency peaks are identified as covariance oscillations of phonon amplitudes by comparison to the phonon dispersion curves [10] and the continuous-wave Raman spectra of KTaO 3 [6].…”

Section: (Received 15 November 1999)mentioning

confidence: 77%

“…Recently, vacuum squeezing of phonons generated by SOR has been predicted by Hu and Nori [3] and demonstrated experimentally by Garret et al in KTaO 3 [4]. They found that the uncertainties of the phonon amplitude and canonical momentum oscillate out of phase at twice the fundamental phonon frequency and temporarily drop below their vacuum noise level.…”

Section: (Received 15 November 1999)mentioning

confidence: 83%

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Impulsive Excitation of Phonon-Pair Combination States by Second-Order Raman Scattering

2000

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The excitation of (100)-oriented KTaO 3 with 25-fs laser pulses impulsively drives phonon-pair combination states via second-order Raman scattering. Oscillations in the phonon-amplitude covariance at the sum and difference frequency of the two involved phonons are observed in a spectrally and temporally resolved pump-probe experiment. Transmission changes of the sample are dominated by contributions of wave vector conserving phonon-pair combinations from the entire Brillouin zone that have maxima in their combined density of states. For low temperatures the temperature dependence of the covariance oscillations of different phonon combinations is reproduced by a quantum-mechanical model. PACS numbers: 78.47. + p, The investigation of coherent phonons in solids has been a field of extensive research since the first observation of coherent phonons in semiconductors [1]. Several excitation mechanisms for coherent lattice vibrations in solids have been identified until now [2]. In the framework of first-order impulsive stimulated Raman scattering coherent phonons are characterized by a nonzero expectation value of the phonon-amplitude oscillating with their eigenfrequency. The driving laser pulse reduces the uncertainty in the amplitudes and the canonical momenta. However, coherent states do not exhibit dynamics in statistic variables like amplitude variances and covariances of phonon modes. Different eigenmodes of the lattice remain uncorrelated.A route to induce macroscopically detectable dynamics in the statistical properties of the lattice is second-order Raman scattering (SOR). Recently, vacuum squeezing of phonons generated by SOR has been predicted by Hu and Nori [3] and demonstrated experimentally by Garret et al. in KTaO 3 [4]. They found that the uncertainties of the phonon amplitude and canonical momentum oscillate out of phase at twice the fundamental phonon frequency and temporarily drop below their vacuum noise level. KTaO 3 is ideally suited for studies on SOR, since for symmetry reasons it exhibits only second-order but no first-order Raman scattering. Thus the excitation of dynamics in the statistical properties of a solid such as amplitude variances (in general associated with squeezed states) and covariances of phonon-pair amplitudes (in general associated with correlations of phonon pairs) can be investigated directly. In this Letter we report on the observation of such combination states of phonon pairs generated by ultrashort light pulses via SOR in a solid: Two oscillators that are decoupled in the absence of perturbation (neglecting anharmonicities) become correlated.To model the second-order Raman excitation in KTaO 3 we consider two harmonic oscillators with amplitudes Q 1 , Q 2 and canonical momenta P 1 , P 2 coupled via the second-order polarizability a ij ≠ 2 a͞≠Q i ≠Q j by excitation with a linearly polarized optical pulse with electric field component E͑t͒. The unperturbed Hamiltonian H 0

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“…This behavior is associated with squeezed phonon states. At T 0 K this is to first order in j ii the result obtained by Garret et al [4,5]. Here, we focus on the consequences of Eq.…”

Section: (Received 15 November 1999)supporting

confidence: 62%

Section: (Received 15 November 1999)mentioning

confidence: 77%

Section: (Received 15 November 1999)mentioning

confidence: 83%

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Impulsive Excitation of Phonon-Pair Combination States by Second-Order Raman Scattering

2000

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“…The explicit form of the coefficients in Eq. (27) for R ′ follows from the general expression (22) for the transition rates…”

Section: Appendix B: the Classical Limitmentioning

confidence: 99%

Switching via quantum activation: A parametrically modulated oscillator

2006

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We study switching between period-two states of an underdamped quantum oscillator modulated at nearly twice its natural frequency. For all temperatures and parameter values switching occurs via quantum activation: it is determined by diffusion over oscillator quasienergy, provided the relaxation rate exceeds the rate of interstate tunneling. The diffusion has quantum origin and accompanies relaxation to the stable state. We find the semiclassical distribution over quasienergy. For T = 0, where the system has detailed balance, this distribution differs from the distribution for T → 0; the T = 0 distribution is also destroyed by small dephasing of the oscillator. The characteristic quantum activation energy of switching displays a typical dependence on temperature and scaling behavior near the bifurcation point where period doubling occurs.

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“…When light interacts with condensed matter, there can also arise squeezed exciton-polariton and phonon-polariton states [24][25][26] and squeezed magnon states [27]. Squeezed states of transverse acoustic phonons interacting with light were observed in experiment [28]. From the theoretical point of view, squeezed polariton states appear under the canonical Bogolubov transformation diagonalizing the matter-radiation Hamiltonian [24,29].…”

Section: Introductionmentioning

confidence: 99%

Atomic squeezing under collective emission

2004

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Atomic squeezing is studied for the case of large systems of radiating atoms, when collective effects are well developed. All temporal stages are analyzed, starting with the quantum stage of spontaneous emission, passing through the coherent stage of superradiant emission, and going to the relaxation stage ending with stationary solutions. A method of governing the temporal behaviour of the squeezing factor is suggested. The influence of a squeezed effective vacuum on the characteristics of collective emission is also investigated.

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Vacuum Squeezing of Solids: Macroscopic Quantum States Driven by Light Pulses

Cited by 175 publications

References 12 publications

Impulsive Excitation of Phonon-Pair Combination States by Second-Order Raman Scattering

Impulsive Excitation of Phonon-Pair Combination States by Second-Order Raman Scattering

Switching via quantum activation: A parametrically modulated oscillator

Atomic squeezing under collective emission

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