Paraffin-coated Vapor Cell Research Articles

Light narrowing over broad temperature range with paraffin-coated vapor cells

This study reports light narrowing in paraffin-coated vapor cells from room temperature 27 to 59 °C, where spin-exchange relaxation is suppressed. By means of a coating lock and eliminating the reservoir effect, an ultra-narrow magnetic resonance linewidth of 0.36 Hz and an atomic coherence lifetime of T2=0.9 s are achieved. In cells free of buffer gas, the narrow linewidth over this broad temperature range is a result of enhanced spin polarization, which is facilitated by the effective suppression of radiation trapping benefiting from the stability of the vapor density. Using such cells in atomic magnetometers, the photon shot noise limit is estimated as 0.2 fT/Hz1/2 and the spin-projection noise limit is estimated as 1.1 fT/Hz1/2. Also, a magnetometer system with the stable coated cell is identified, which demonstrates the potential for achieving relatively stable magnetometer sensitivity without precisely controlling the cell temperature. The long coherence lifetime and the broad operating temperature range expand the potential applications of quantum memory and other quantum sensors such as atomic clocks.

Observation of spin bistability with paraffin-coated vapor cells

Observation of spin bistability with paraffin-coated vapor cells

Hybrid optical pumping of K and Rb atoms in a paraffin coated vapor cell.

Dynamic hybrid optical pumping effects with a radio-frequency field-driven nonlinear magneto-optical rotation scheme are studied in a dual-species paraffin coated vapor cell. By pumping K atoms and probing Rb87 atoms, we achieve an intrinsic magnetic resonance linewidth of 3Hz, and the observed resonance is immune to power broadening and light-shift effects. Such an operation scheme shows favorable prospects for atomic magnetometry applications.

Large magnetic shielding factor measured by nonlinear magneto-optical rotation

A passive magnetic shield was designed and constructed for magnetometer tests for the future neutron electric dipole moment experiment at TRIUMF. The axial shielding factor of the cylindrical magnetic shield was measured using a magnetometer based on non-linear magneto-optical rotation of the plane of polarized laser light upon passage through a paraffin-coated vapor cell containing natural Rb at room temperature. The laser was tuned to the Rb D1 line, near the 85Rb F=2→2,3 transition. The shielding factor was measured by applying an axial field externally and measuring the magnetic field internally using the magnetometer. The axial shielding factor was determined to be (1.3±0.1)×107, from an applied axial field of 1.45μT in the background of Earth׳s magnetic field.

Amplified slow light beam splitter and 1 s optical memory

Using atomic motion to coherently spread light information stored in atoms provides a means to manipulate atom-light interactions. We demonstrate light splitting with moving atoms in a paraffin-coated vapor cell by using phase-sensitive degenerate four-wave mixing, or self-rotation. This scheme amplifies the slow light beam splitter signal, and, in the meantime, maintains the phase coherence between the beam-splitter channels. Light storage efficiency in the beam-splitting channel can also be enhanced. Furthermore, we demonstrate an optical memory exceeding 1 s, taking advantage of the gain from self-rotation and an atomic coherence composed of a fast-decaying part and a slow-decaying part. These results should find applications in optical memory, optical routers, and atomic coherence control.

Spatial transport of atomic coherence in electromagnetically induced absorption with a paraffin-coated Rb vapor cell.

We report the spatial transport of spontaneously transferred atomic coherence (STAC) in electromagnetically induced absorption (EIA), which resulted from moving atoms with the STAC of the 5S(1/2) (F = 2)-5P(3/2) (F' = 3) transition of (87)Rb in a paraffin-coated vapor cell. In our experiment, two channels were spatially separate; the writing channel (WC) generated STAC in the EIA configuration, and the reading channel (RC) retrieved the optical field from the spatially transported STAC. Transported between the spatially separated positions, the fast light pulse of EIA in the WC and the delayed light pulse in the RC were observed. When the laser direction of the RC was counter-propagated in the direction of the WC, we observed direction reversal of the transported light pulse in the EIA medium. Furthermore, the delay time, the magnitude, and the width of the spatially transported light pulse were investigated with respect to the distance between the two channels.

Electromagnetically induced transparency in paraffin-coated vapor cells

Antirelaxation coatings in atomic vapor cells allow ground-state coherent spin states to survive many collisions with the cell walls. This reduction in the ground-state decoherence rate gives rise to ultranarrow-bandwidth features in electromagnetically induced transparency (EIT) spectra, which can form the basis of, for example, long-time scale slow and stored light, sensitive magnetometers, and precise frequency standards. Here we study, both experimentally and theoretically, how Zeeman EIT contrast and width in paraffin-coated rubidium vapor cells are determined by cell and laser-beam geometry, laser intensity, and atomic density. Using a picture of Ramsey pulse sequences, where atoms alternately spend ``bright'' and ``dark'' time intervals inside and outside the laser beam, we explain the behavior of EIT features in coated cells, highlighting their unique characteristics and potential applications.

파라핀이 코팅된 Rb 증기 셀에서 비선형 광자기 효과 신호

본 연구에서는 파라핀이 코팅된 Rb원자 증기 셀을 이용하여 <TEX>$^{87}Rb$</TEX> <TEX>$D_1$</TEX>전이선의 Hanle스펙트럼과 비선형 광자기 효과 신호를 조사하였다. 파라핀 코팅 증기 셀의 효과에 의한 좁은 스펙트럼 폭을 가진 영역과 순수 증기 셀에서 얻을 수 있는 넓은 스펙트럼폭을 가진 이중구조의 Hanle 스펙트럼을 관측할 수 있었다. 스펙트럼에 나타난 이중구조에서 좁은 선폭 영역의 선폭은 1 kHz로 측정되었고, 스펙트럼 크기는 전체 스펙트럼에 대해서 10%로 측정되었다. 또한, Hanle 스펙트럼에 대응되는 이중 미분형태의 비선형 광자기 신호를 관측하였으며, 기울기가 급격하게 변하는 비선형 광자기 신호의 기울기는 레이저의 출력이 <TEX>$200{\mu}W$</TEX>일 때 대략 10 mV/<TEX>${\mu}T$</TEX>였다. In our study, the Hanle spectrum and nonlinear magneto-optic effect (NMOE) signals were observed as a function of magnetic field on <TEX>$D_1$</TEX> line of <TEX>$^{87}Rb$</TEX> atoms contained in a paraffin coated vapor cell. We observed the double structure from the Hanle and the NMOE spectrum in the paraffin coated Rb vapor cell. The narrow spectral width of the narrow resonance signal is approximately 1 kHz and the magnitude is approximately 10 percent of the total spectrum. Also, the NMOE signals corresponding to the Hanle configuration consisted of two different dispersion-like features. At the near zero magnetic field, a sharp slope signal was centered, and its value was 10 mV/<TEX>${\mu}T$</TEX> with laser power was <TEX>$200{\mu}W$</TEX>.

파라핀 코팅된 Rb원자 증기 셀에서 원자결맞음 분광

본 연구에서는 파라핀으로 코팅된 Rb원자 증기셀에서 전자기 유도 투과(Electromagnetically induced transparency: EIT)와 Hanle 스펙트럼을 관측하고 분석하였다. EIT스펙트럼은 독립적으로 발진하는 두 대의 외부 공진형 반도체 레이저를 이용하여 <TEX>$^{85}Rb$</TEX>의 <TEX>$D_1$</TEX> 전이선(<TEX>$F_g=2$</TEX>, <TEX>$3{\rightarrow}F_e=3$</TEX>)에서 관측하였고, Hanle 스펙트럼은 한대의 외부 공진형 반도체를 이용하여 <TEX>$^{87}Rb$</TEX>의 <TEX>$D_1$</TEX> 전이선(<TEX>$F_g=2{\rightarrow}F_e=1$</TEX>)의 자기 부준위 사이의 3준위 <TEX>$\Lambda$</TEX>형 구도에서 관측하였다. 파라핀 코팅된 루비듐 증기 셀에서 Hanle 스펙트럼에서 이중구조를 관측할 수 있었고,증기셀 주변의 자기장의 세기를 변화시켜서 얻은Hanle 스펙트럼에서 이중구조의 스펙트럼 형태의 변화를 외부자기장의 방향과 크기에 따른 조사하였다. 이때 이중 구조에서 좁은 영역의 스펙트럼의 선폭은 200 Hz로 측정되었다. We investigated the electromagnetically induced transparency (EIT) and the Hanle spectrum in a paraffin coated Rb vapor cell. The EIT spectrum was observed in the <TEX>$F_g=2$</TEX>, <TEX>$3{\rightarrow}F_e=3$</TEX> transition of the <TEX>$^{85}Rb$</TEX> <TEX>$D_1$</TEX>-line by using two independent external cavity diode lasers, and the Hanle spectrum was observed by using one external cavity diode laser in the <TEX>$\Lambda$</TEX>-type scheme between the Zeeman sublevels of the <TEX>$F_g=2{\rightarrow}F_e=1$</TEX> transition of the <TEX>$^{87}Rb$</TEX> <TEX>$D_1$</TEX>-line. In the Hanle spectrum, we could observe the dual-structured spectrum in the paraffin coated vapor cell. We investigated the dual-structured lineshape by applying an external magnetic field, and varying the direction of the magnetic field. The narrow linewidth of dual-structured EIT was measured to be approximately 200 Hz.

Characterizing the spin state of an atomic ensemble using the magneto-optical resonance method

Quantum information protocols utilizing atomic ensembles require preparation of a coherent spin state (CSS) of the ensemble as an important starting point. We investigate the magneto-optical resonance method for characterizing a spin state of cesium atoms in a paraffin coated vapor cell. Atoms in a constant magnetic field are subject to an off-resonant laser beam and an RF magnetic field. The spectrum of the Zeeman sub-levels, in particular the weak quadratic Zeeman effect, enables us to measure the spin orientation, the number of atoms, and the transverse spin coherence time. Notably the use of 894nm pumping light on the D1-line, ensuring the state F=4, m_F=4 to be a dark state, helps us to achieve spin orientation of better than 98%. Hence we can establish a CSS with high accuracy which is critical for the analysis of the entangled states of atoms.