Magnon Squeezing in an Antiferromagnet: Reducing the Spin Noise below the Standard Quantum Limit

Zhao, Jimin; Bragas, Andrea V.; Lockwood, D. J.; Merlín, R.

doi:10.1103/physrevlett.93.107203

Cited by 104 publications

(110 citation statements)

References 33 publications

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“…35 In metals and dielectrics, however, experimental studies of such mechanisms on the subpicosecond time scale are rare. 16,[23][24][25]36 On a longer time scale, the possibility to change the magnetization of a medium via polarization-sensitive optical transitions has been known since the 1960s, when a helicity-dependent lightinduced magnetization was predicted 37,38 and observed 39 in a transparent paramagnetic medium subjected to 30 ns circularly polarized pulses. This phenomenon was named the inverse Faraday effect.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, second-order ISRS was shown to be the mechanism for the generation of a magnon squeezed state. 16 However, only recently first-order stimulated Raman scattering was suggested as the mechanism for the experimentally observed coherent magnon generation. 23 An unambiguous demonstration of the generation of coherent magnons via first-order ISRS in FeBO 3 was reported in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…1 Already the first observation of ultrafast ͑within 0.1 ps͒ light-induced demagnetization in nickel films 2 suggested that a conventional thermodynamical approach to the problem is not justified. [3][4][5] New theoretical models have to be worked out in order to understand recent results such as ultrafast light-induced demagnetization, 2,[4][5][6][7][8][9][10][11][12] phase transitions, 13,14 magnetic-order sensitive excitation of phonon modes, 15 generation of a magnon squeezed state, 16 excitation of coherent spin precession, [17][18][19][20][21][22][23][24][25] and the magnetization reversal by a single 40 fs laser pulse. 26 The theoretical models proposed so far to explain these exciting experimental observations [27][28][29][30][31][32][33][34] leave several important issues open for further discussion.…”

Section: Introductionmentioning

confidence: 99%

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Impulsive excitation of coherent magnons and phonons by subpicosecond laser pulses in the weak ferromagnetFeBO3

et al. 2008

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Coherent magnons and phonons are excited by subpicosecond laser pulses in the weak ferromagnet FeBO 3 . Impulsive stimulated Raman scattering ͑ISRS͒ is proven to be the microscopic mechanism of the excitation. It is shown that coherent magnons can be excited by both linearly and circularly polarized laser pulses where the efficiency of the process depends on the mutual orientation of the magnetic and crystallographic axes and the light propagation direction. The strong ellipticity of the ferromagnetic magnon mode is demonstrated, both experimentally and theoretically, to be essential for the excitation and observation of such coherent magnons. Because of this ellipticity, the amplitude of the coherent magnons excited by linearly polarized light may exceed by 2 orders of magnitude the amplitude of those excited by circularly polarized light. The primary difference between the excitation of coherent magnons by linearly polarized pulses via ISRS and via the earlier reported process of photoinduced magnetic anisotropy is discussed. Furthermore, the ISRS process is found to be responsible for the excitation of two optical phonon branches ͑8.4 and 12.1 THz͒ observed in our experiments. A coherent excitation, with a temperature-independent frequency of 0.7 THz, has also been observed in the magnetically ordered phase but could not be assigned to any optical phonon modes known in FeBO 3 . The well-pronounced dependence of the amplitude of this mode on temperature suggests that this mode of nonmagnetic origin becomes Raman active only in the magnetically ordered phase and, therefore, can be excited and observed only below the Néel temperature.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impulsive excitation of coherent magnons and phonons by subpicosecond laser pulses in the weak ferromagnetFeBO3

et al. 2008

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“…In this case the mechanism is a three-phonon parametric process analogous to that used to produce coherent two-photon states. This type of experiment has been extended to the creation of coexcited coherent and squeezed vibrations 10 and to squeezed spin waves 14 in MnF 2 but in no case has the noise been unequivocally shown to fall below the quantum limit because of the difficulty of making direct optical measurements of the variance of atomic displacements in condensed matter. 8 More recently, femtosecond x-ray diffraction has been used to probe the statistics of lattice vibrations following intense ͑several millijoule per square centimeter͒ optical excitation of single crystal Bi.…”

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confidence: 99%

Absence of phase-dependent noise in time-domain reflectivity studies of impulsively excited phonons

Hussain

Andrews

2010

Phys. Rev. B

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There have been several reports of phase-dependent noise in time-domain reflectivity studies of optical phonons excited by femtosecond laser pulses in semiconductors, semimetals, and superconductors. It was suggested that such behavior is associated with the creation of squeezed phonon states although there is no theoretical model that directly supports such a proposal. We have experimentally re-examined the studies of phonons in bismuth and gallium arsenide, and find no evidence of any phase-dependent noise signature associated with the phonons. We place an upper limit on any such noise at least 40-50 dB lower than previously reported. DOI: 10.1103/PhysRevB.81.224304 PACS number͑s͒: 78.47.jg, 63.20.Ϫe, 42.50.Lc Coherent phonons in semiconductors, superconductors, metals, and insulators have been widely studied in the time domain since the first report of their excitation by femtosecond laser pulses in about 1990.1,2 The most general excitation mechanism is impulsive stimulated Raman scattering ͑ISRS͒.3 A special case of ISRS in opaque materials is sometimes referred to as the displacive mechanism 1 and is associated with electronic excitation from bonding to antibonding orbitals. Longitudinal optical phonons in semiconductors can also be driven by the transient polarization associated with the screening of surface space-charge fields following interband excitation. 2The amplitude of a phonon mode may be decomposed into two quadrature components with the time dependences cos t and sin t. In a coherent state, the closest quantum counterpart to a classical field, the fluctuations in the two quadratures have the same variance and are randomly distributed in phase. The product of the variances in each quadrature is the minimum allowed by the Heisenberg uncertainty principle. Minimum uncertainty states in which the fluctuations in one quadrature have a variance that falls below the zero-point quantum noise level are called squeezed states. 4 Squeezed electromagnetic fields were experimentally studied for the first time in the mid-1980s ͑Ref. 5͒ and nonclassical light is now an established area of research.6 A phasedependent nonlinear process is necessary to generate a squeezed state. For example, squeezed optical fields can be produced by parametric amplification or four-wave mixing. Recently, there has been interest in extending the study of nonclassical fields to lattice vibrations in condensed matter but except for a few studies of squeezing, 7-12 and amplitude collapse and revival, 13 there has been relatively little work on phonon fields. Squeezing of phonons generated by secondorder Raman scattering was predicted 7 and later reported 9,11 in low temperature, femtosecond pump-probe transmission measurements on KTaO 3 . In this case the mechanism is a three-phonon parametric process analogous to that used to produce coherent two-photon states. This type of experiment has been extended to the creation of coexcited coherent and squeezed vibrations 10 and to squeezed spin waves 14 in MnF 2 but in no case has the...

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“…In recent years, quantum squeezing has expanded tremendously to different systems such as photon [10][11][12][13] and phonons [14,15]. Recently, squeezed magnons (collective spin-wave excitation) in solid-state materials have garnered much attention [16][17][18][19] as reported in the cubic antiferromagnetic insulators XF 2 (X ≡ Mn and Fe) through the impulsive stimulated Raman scattering [16,17]. A possible realization in onedimensional optical lattice which maps to a ferromagnetic spin chain [20] has also been proposed [21].…”

Section: Introductionmentioning

confidence: 99%

Squeezed Dirac and topological magnons in a bosonic honeycomb optical lattice

Owerre¹,

Nsofini²

2017

J. Phys.: Condens. Matter

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Quantum information storage using charge-neutral quasiparticles are expected to play a crucial role in the future of quantum computers. In this regard, magnons or collective spin-wave excitations in solid-state materials are promising candidates in the future of quantum computing. Here, we study the quantum squeezing of Dirac and topological magnons in a bosonic honeycomb optical lattice with spin-orbit interaction by utilizing the mapping to quantum spin-1/2 XYZ Heisenberg model on the honeycomb lattice with discrete Z2 symmetry and a Dzyaloshinskii-Moriya interaction. We show that the squeezed magnons can be controlled by the Z2 anisotropy and demonstrate how the noise in the system is periodically modified in the ferromagnetic and antiferromagnetic phases of the model. Our results also apply to solid-state honeycomb (anti)ferromagnetic insulators.

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Magnon Squeezing in an Antiferromagnet: Reducing the Spin Noise below the Standard Quantum Limit

Cited by 104 publications

References 33 publications

Impulsive excitation of coherent magnons and phonons by subpicosecond laser pulses in the weak ferromagnetFeBO3

Impulsive excitation of coherent magnons and phonons by subpicosecond laser pulses in the weak ferromagnetFeBO3

Absence of phase-dependent noise in time-domain reflectivity studies of impulsively excited phonons

Squeezed Dirac and topological magnons in a bosonic honeycomb optical lattice

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