Equilibrium temperature of laser cooled atoms in squeezed vacuum

It is shown that by squeezing the vacuum fluctuations of the electromagnetic field the quantum fluctuations of the optical forces exerted on laser cooled two-level atoms, can be dramatically modified. Under certain conditions, this modification in concert with the enhanced average forces can lead to equilibrium temperatures below those attained under normal vacuum fluctuations

Linewidth reduction and frequency stabilization of a semiconductor laser with a combination of FM sideband locking and optical feedback

We describe a novel method for semiconductor laser noise reduction that uses a combination of optical and electronic feedback. A Doppler-free Faraday resonance in Cs vapor provided both optical feedback and discrimination for an electronic feedback scheme incorporating FM sideband spectroscopy. The introduction of electronic feedback further reduced the low-frequency fluctuation noise power by more than 2 orders of magnitude, resulting in a linewidth of 1.4 kHz

Amplitude noise reduction in semiconductor lasers with weak, dispersive optical feedback

We present the theory and measurements of the amplitude noise spectrum from a semiconductor laser with weak optical feedback (Pfb/Pout ~10^-6) from an external cavity containing an element of dispersive loss. The laser noise is found to be reduced over most of the low-frequency spectrum, although an increase in the noise is observed at frequencies corresponding to multiples of the external-cavity free spectral range. The low-frequency noise reduction closely follows theoretical predictions, and a reduction of as much as 7 dB is measured at an injection current of 1.5 times the threshold current. The potential of this method for contributing to the production of amplitude-squeezed light is discussed

Self-quenching of the semiconductor laser linewidth below the Schawlow-Townes limit by using optical feedback

We demonstrate theoretically and experimentally self-quenching of the fundamental semiconductor laser frequency fluctuations to a level that is orders of magnitude below the Schawlow-Townes limit for a solitary laser. It is shown that the main operative mechanism is the combined action of a frequency-dependent internal loss and amplitude-to-phase coupling. The internal frequency-dependent loss is introduced by means of spectrally narrow external optical feedback, which provides a strong frequency-dependent dispersion. Linewidth reduction by a factor of 2 X 10^3 is demonstrated by using a narrow Doppler-free Faraday resonance in Cs vapor

Semiconductor laser quantum noise limits

The quantum mechanical limits to the fundamental noise performance of semiconductor lasers are reviewed. Recent advances in pushing the laser noise below theses limits are then discussed with emphasis on pump suppression, electronic feedback, and correlation techniques such as optical feedback. It is found that narrow-linewidth semiconductor lasers with sub-shot- noise photon statistics are within the reach of current technology

Generation of amplitude-squeezed light from a pump-suppressed semiconductor laser with dispersive optical feedback

Amplitude-squeezed states are generated from a room-temperature semiconductor laser using a combination of pump suppression and dispersive optical feedback. The laser amplitude noise is found to be sensitive to extremely weak feedback levels, of the order of 10^(-8) of the output power. a reduction of the noise from 2% below the standard quantum limit (SQL) under free-running conditions to 19% below the SQL under optimal feedback conditions is obtained. A single mode theory is presented but is found to be inadequate in explaining the measured dependence of the noise reduction on the feedback power. A multimode theory including asymmetrical cross-mode nonlinear gain is proposed to explain this discrepancy

Laser Cooling With Two Wave Mixing

The process of laser cooling in a quasi resonant standing laser wave is one of the principal techniques of laser cooling of free atoms. It will be shown that the nonlinear interaction between the counter propagating waves in a standing wave have a profound affect on the mechanical manifestations of the light on the atoms. This can be understood simply by noting that in the Two Wave Mixing (TWM) process, a momentum kick of 2ℏk is transferred to the atom, as a photon is absorbed from one wave and emitted into the counter propagating wave. This process is in fact responsible for the so called "Dipole force" Or "Stimulated Molasses" and has been verified experimentally!. However, since the TWM process requires high laser intensity under normal conditions it does not usually lead to lower equilibrium temperatures. Nevertheless, It has been shown that the TWM process can be modified when the normal decay rates of the atom are altered. This modification can give rise to the appearance of the TWM at lower intensity and can even change its lineshape. This in turn have an important implications on the laser cooling process in a standing wave. Among the important effects: (i) The appearance of the stimulated force at lower intensity when the dipole decay rate is increased by dephasing events.(ii) The appearance of a narrow resonance characterized by the ground state decay in an open system. (iii) The modification of the stimulated force when the quantum fluctuations of the vacuum field are modified by quadrature squeezing. Processes (ii) and (iii) can change the sign of the stimulated force from a heating force to a cooling force at the red side of the atomic resonance and give additional cooling force much larger than the radiation pressure force

Implementasi aplikasi i-kurma terhadap peningkatan pembiayaan kur dengan akad murabahah pada Bank Syariah Indonesia kantor cabang Sidoarjo

Implementasi Aplikasi I-Kurma terhadap peningkatan pembiayaan KUR dengan akad murabahah pada Bank Syariah Indonesia cabang Sidoarjo. Masa pandemi membuat mobilitas terhambat yang menimbulkan dampak pada perbankan. Agar perbankan dapat meningkatkan kinerjanya, maka diperlukannya penggunaan teknologi digital. Dengan mengetahui peran UKM pada peningkatan perekonomian cukup penting bagi negara, maka perbankan hadir untuk mendukung UKM dengan menawarkan produk pembiayaan KUR, yang diharapkan agar keuangan Islam iklusif dapat terwujud. Untuk itu Bank Syariah Indonesia memiliki aplikasi I-Kurma guna mempermudah pembiayaan yang dapat menunjang perekonomian negara melalui KUR untuk UKM yang memerlukan pembiayaan. Sehingga dapat diambil rumusan masalah yaitu bagaimana implementasi aplikasi I-kurma terhadap penyaluran pembiayaan KUR dengan akad murabahah dan bagaimana peningkatan pembiayaan KUR dengan akad murabahah menggunakan aplikasi I-kurma. Metodologi pada penelitian ini menggunakan pendekatan penelitian kualitatif berjenis deskriptif. Dengan menggunakan observasi, wawancara dan dokumentasi terkait penelitian tersebut, yang digunakan sebagai sumber penelitian primer dan sumber sekunder. Yang kemudian sumber tersebut dianalisis sehingga dapat ditarik sebuah kesimpulan. Hasil dari penelitian ini adalah aplikasi I-Kurma pada Bank Syariah Indonesia telah bekerja sesuai dengan tujuan pembuatan aplikasi tersebut yaitu untuk memudahkan pemrosesan pembiayaan KUR dengan akad murabahah. Aplikasi tersebut berdampak baik terhadap kemudahan pemrosesan pembiayaan KUR dengan akad murabahah karena dengan kecanggihan aplikasi I-Kurma, pemrosesan pembiayaan dapat dikelola dengan lebih efisien. Namun dengan kemudahan tersebut aplikasi I-Kurma tidak dapat mempengaruhi peningkatan pembiayaan KUR dengan akad murabahah secara langsung. Peningkatan pembiayaan KUR dengan akad murabahah dipengaruhi oleh faktor lainnya yaitu faktor internal dan faktor eksternal. Bank Syariah Indonesia diharapkan dapat meningkatkan pembaruan fitur aplikasi I-Kurma seiring dengan kebutuhan pengguna agar dapat lebih efektif dan efisien. Bagi penulis selanjutnya diharapkan dapat memperbanyak kajian terkait peningkatan pembiaayn KUR dengan akad murabahah menggunakan aplikasi I-Kurma

A comparison of German and American listeners' extra musical associations with popular music genres

This causal comparative study examined the consistency with which listeners from two cultures (Germany and the USA) associate extra musical concepts with four popular music genres (German folksy, country, punk, and hip-hop). The results showed that for internationally recognized genres (country, punk and hip-hop), the two countries made similar association patterns for all eight concepts measured (ethnicity, rural vs. urban culture, age, trustworthiness, expertise, attractiveness, friendliness, and political ideology). The study also revealed instances where the countries differed, such as hip-hop's association with ethnicity and most of the German folksy associations. The results are discussed in light of models of musical meaning. Furthermore, an integration of societal-level and individual-level theories predicts these similarities and differences. The theories include massification, glocalization, and cognitive schemas

Effects of optical feedback with dispersive loss on the amplitude noise and relaxation resonance of semiconductor lasers

Optical feedback from an external cavity containing an element of dispersive loss was used to reduce the amplitude noise of a semiconductor laser. At feedback levels of P_(fb)/P_(out) ≈ 10^(-2)), a maximum amplitude noise reduction of 16 decibel was measured close to threshold but the potiential for reduction was reduced considerably at higher injection currents as the laser noise approached the shot noise limit. In addition, the threshold current decreased and the linewidth was reduced to 10 kHz. The relaxation oscillation peak in the amplitude noise spectrum was also found to be dramatically suppressed and we find evidence that the relaxation resonance can be moved to much higher frequencies using optical feedback techniques