Resonance fluorescence has played a major role in quantum optics with predictions and later experimental confirmation of nonclassical features of its emitted light such as antibunching or squeezing. In the Rayleigh regime where most of the light originates from the scattering of photons with subnatural linewidth, antibunching would appear to coexist with sharp spectral lines. Here, we demonstrate that this simultaneous observation of subnatural linewidth and antibunching is not possible with simple resonant excitation. Using an epitaxial quantum dot for the two-level system, we independently confirm the single-photon character and subnatural linewidth by demonstrating antibunching in a Hanbury Brown and Twiss type setup and using high-resolution spectroscopy, respectively. However, when filtering the coherently scattered photons with filter bandwidths on the order of the homogeneous linewidth of the excited state of the two-level system, the antibunching dip vanishes in the correlation measurement. Our observation is explained by antibunching originating from photon-interferences between the coherent scattering and a weak incoherent signal in a skewed squeezed state. This prefigures schemes to achieve simultaneous subnatural linewidth and antibunched emission.Resonance fluorescence has played a major role in quantum optics with predictions and later experimental confirmation of nonclassical features of its emitted light such as antibunching or squeezing. In the Rayleigh regime where most of the light originates from the scattering of photons with subnatural linewidth, antibunching would appear to coexist with sharp spectral lines. Here, we demonstrate that this simultaneous observation of subnatural linewidth and antibunching is not possible with simple resonant excitation. Using an epitaxial quantum dot for the two-level system, we independently confirm the single-photon character and subnatural linewidth by demonstrating antibunching in a Hanbury Brown and Twiss type setup and using high-resolution spectroscopy, respectively. However, when filtering the coherently scattered photons with filter bandwidths on the order of the homogeneous linewidth of the excited state of the two-level system, the antibunching dip vanishes in the correlation measurement. Our observation is explained by antibunching originating from photon-interferences between the coherent scattering and a weak incoherent signal in a skewed squeezed state. This prefigures schemes to achieve simultaneous subnatural linewidth and antibunched emission.

arXiv:2005.11800Physical Review LettersOct 23, 202060 citations

Subnatural linewidth for probe absorption in an electromagnetically-induced-transparency medium due to Doppler averaging

S. M. Iftiquar, Gautam Karve, Vasant Natarajan A

We obtain subnatural linewidth (i.e., $<\ensuremath{\Gamma}$) for probe absorption in room-temperature Rb vapor using electromagnetically induced transparency (EIT) in a $\ensuremath{\Lambda}$ system. For stationary atoms, the EIT dip for a resonant control laser is roughly one-half as wide as the control Rabi frequency ${\ensuremath{\Omega}}_{c}$. But in thermal vapor, the moving atoms fill the transparency band so that the final EIT dip remains subnatural even when ${\ensuremath{\Omega}}_{c}⪢\ensuremath{\Gamma}$. We observe a linewidth of $\ensuremath{\Gamma}/4$ for ${\ensuremath{\Omega}}_{c}=8\ensuremath{\Gamma}$ in the ${D}_{2}$ line of Rb.We obtain subnatural linewidth (i.e., $<\ensuremath{\Gamma}$) for probe absorption in room-temperature Rb vapor using electromagnetically induced transparency (EIT) in a $\ensuremath{\Lambda}$ system. For stationary atoms, the EIT dip for a resonant control laser is roughly one-half as wide as the control Rabi frequency ${\ensuremath{\Omega}}_{c}$. But in thermal vapor, the moving atoms fill the transparency band so that the final EIT dip remains subnatural even when ${\ensuremath{\Omega}}_{c}⪢\ensuremath{\Gamma}$. We observe a linewidth of $\ensuremath{\Gamma}/4$ for ${\ensuremath{\Omega}}_{c}=8\ensuremath{\Gamma}$ in the ${D}_{2}$ line of Rb.

arXiv:0711.0064Physical Review AJun 9, 200877 citations

Subnatural Linewidth Laser Spectroscopy

Hiroshi Takuma, Fujio Shimizu, Kazuko Shimizu

Springer eBooksJan 1, 19860 citations

{D}_{2}

line of Rb.