Experimental determination of the dynamics of a molecular nuclear wave packet via the spectra of spontaneous emission

Dunn, Thomas J.; Sweetser, John N.; Radzewicz, Czesław

doi:10.1103/physrevlett.70.3388

Cited by 128 publications

(65 citation statements)

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“…Transient quantum squeezing has also been created and observed in the motion of molecular nuclei [16] and of terahertz-frequency phonons in an atomic lattice on picosecond timescales [21]. While [37], [16], and [21] all produce quantum squeezed states of motion, when it comes to potential applications, they do not have the same advantages as the steady-state squeezing of the engineered, high-Q mechanical resonator that we deal with in this work. Moreover, a mesoscopic membrane is, in many ways, a more "classical" object than a collection of ions or phonons, and quantum manipulation of larger, more macroscopic systems is a current goal of experimental physics.…”

Section: Introductionmentioning

confidence: 93%

“…More generally, other non-commuting observable pairs can be squeezed, and quantum squeezed states 1 have been created and detected in such varied systems as optical [49] and microwave [66] modes, the motion of trapped ions [37], and spin states in an ensemble of cold atoms [24]. Transient quantum squeezing has also been created and observed in the motion of molecular nuclei [16] and of terahertz-frequency phonons in an atomic lattice on picosecond timescales [21]. While [37], [16], and [21] all produce quantum squeezed states of motion, when it comes to potential applications, they do not have the same advantages as the steady-state squeezing of the engineered, high-Q mechanical resonator that we deal with in this work.…”

Section: Introductionmentioning

confidence: 99%

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Quantum squeezing of motion in a mechanical resonator

Wollman

Lei

Weinstein

et al. 2015

Science

668

566

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showed patience and understanding. He gave me the opportunity to work on a variety of interesting projects, from graphene, to superconducting amplifiers, to the results discussed here. Most of all, Keith taught me to be more decisive, to take more risks, and to do whatever it takes. Our theory collaborators on the squeezing project, Aashish Clerk, Florian Marquardt, and especially Andreas Kronwald, gave essential support before, during, and after measurement-taking.Although they sometimes seemed puzzled at the number of ways that things can go wrong in experimental work, they showed great patience as we tried to make their proposal a reality.I couldn't have made it through grad school without the support of my friends: Paul, Branimir, Helge, Alice, Tristan, Chris, Kris, Doron, Mo, and Carly. They gave me something to look forward to throughout the week, and something to talk about other than grad school. where an optical or microwave cavity is coupled to the mechanics in order to control and read out the mechanical state. In the proposal, two pump tones are applied to the cavity, each detuned from the cavity resonance by the mechanical frequency. The pump tones establish and couple the mechanics to a squeezed reservoir, producing arbitrarily-large, steady-state squeezing of the mechanical motion.In this dissertation, I describe two experiments related to the implementation of this proposal in an electromechanical system. I also expand on the theory presented in [30] to include the effects of squeezing in the presence of classical microwave noise, and without assumptions of perfect alignment of the pump frequencies.In the first experiment, we produce a squeezed thermal state using the method of Kronwald et. al..We perform back-action evading measurements of the mechanical squeezed state in order to probe the noise in both quadratures of the mechanics. Using this method, we detect single-quadrature fluctuations at the level of 1.09 ± 0.06 times the quantum zero-point motion.In the second experiment, we measure the spectral noise of the microwave cavity in the presence of the squeezing tones and fit a full model to the spectrum in order to deduce a quadrature variance of 0.80 ± 0.03 times the zero-point level. These measurements provide the first evidence of quantum squeezing of motion in a mechanical resonator.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Quantum squeezing of motion in a mechanical resonator

Wollman

Lei

Weinstein

et al. 2015

Science

668

566

View full text Add to dashboard Cite

show abstract

“…4 support a harmonic character rather than a superposition of excited vibrational states in an anharmonic potential as explanation for the HFM and LFM. The spectral signature of the HFM further reveals that its wavenumber is not just the second harmonic of the LFM, because then its amplitude in the 3D spectrum would not be maximal at the turning points but exactly in between where the wave packet passes twice per vibrational period (31,33). Therefore, the HFM is a further vibrational mode induced in the photoproduct.…”

Section: Third-order 3d Spectrummentioning

confidence: 99%

Multidimensional spectroscopy of photoreactivity

Ruetzel¹,

Diekmann²,

Nuernberger³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Coherent multidimensional electronic spectroscopy is commonly used to investigate photophysical phenomena such as light harvesting in photosynthesis in which the system returns back to its ground state after energy transfer. By contrast, we introduce multidimensional spectroscopy to study ultrafast photochemical processes in which the investigated molecule changes permanently. Exemplarily, the emergence in 2D and 3D spectra of a cross-peak between reactant and product reveals the cis-trans photoisomerization of merocyanine isomers. These compounds have applications in organic photovoltaics and optical data storage. Cross-peak oscillations originate from a vibrational wave packet in the electronically excited state of the photoproduct. This concept isolates the isomerization dynamics along different vibrational coordinates assigned by quantum-chemical calculations, and is applicable to determine chemical dynamics in complex photoreactive networks.photoreactive processes | ultrafast spectroscopy | 2D spectroscopy | vibrational coherence A basic objective of physical chemistry is to determine the mechanisms underlying chemical reactions. Fundamental insights into these are provided by femtosecond time-resolved spectroscopy, even below the timescale of molecular vibrations (1). The major challenge of ultrafast photochemistry is to identify isolated signatures of reactants, intermediates, and products, whose spectral bands often overlap. Here we show that such ambiguities are unraveled by coherent multidimensional electronic spectroscopy, e.g., 2D and 3D spectroscopy, where the correlation of a system's excitation and emission frequencies is measured separating features that otherwise superpose. We detect photoreactivity directly via cross-peaks in multidimensional spectra. This opens the broad field of femtochemistry (1) to the multidimensional concept.Two-dimensional electronic spectroscopy (2-5) was primarily implemented for studying photophysical phenomena such as energy transfer in multichromophore light-harvesting systems or other excitonically coupled systems (6-11). Recently, charge transfer has also been investigated (12, 13). Here we are interested in photochemical processes leading to ground-state product species with a molecular configuration that is different from the initial reactant. As a general extension of 2D spectroscopy, 3D representations provide an even more detailed picture. Coherent 3D spectroscopy has been introduced to infrared spectroscopy (14, 15), and recently to electronic spectroscopy for isolating excitonic coherences (16, 17), for liquid-and gas-phase model systems (18)(19)(20), and for analyzing photosynthetic lightharvesting (21,22). Regarding these approaches, one has to differentiate between fifth-order experiments (14, 15, 19) for effects of higher nonlinearity (e.g., three-point frequency-fluctuation correlation functions) (14) and third-order techniques (20)(21)(22)(23)(24), as demonstrated here to unravel photochemical reactions.The principal idea of multidimensional spectrosc...

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“…The BHD can be extended [8][9][10][11][12] to multimode signals and to measure other distributions like the positive P-distribution. The BHD is for optical fields and methods have been developed for reconstructing the vibrational state of molecules [13] and spin systems [14]. For measruing the quantum states of the modes of a cavity, atoms with properly chosen energy levels can be used as probes [15].…”

Section: Introductionmentioning

confidence: 99%

Quantum-state tomography of complex multimode fields using array detectors

Sivakumar¹,

Agarwal²

2001

Phys. Rev. A

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We demonstrate that it is possible to use the balanced homodyning with array detectors to measure the quantum state of correlated two-mode signal field. We show the applicability of the method to fields with complex mode functions, thus generalizing the work of Beck(Phys. Rev. Lett. 84, 5748 (2000)) in several important ways. We further establish that, under suitable conditions, array detector measurements from one of the two ouputs is sufficient to determine the quantum state of signal. We show the power of the method by reconstructing a truncated Perelomov state which exhibits complicated structure in the joint probability density for the quadratures.

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Experimental determination of the dynamics of a molecular nuclear wave packet via the spectra of spontaneous emission

Cited by 128 publications

References 10 publications

Quantum squeezing of motion in a mechanical resonator

Quantum squeezing of motion in a mechanical resonator

Multidimensional spectroscopy of photoreactivity

Quantum-state tomography of complex multimode fields using array detectors

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