Phonon-bottlenecked spin relaxation of Er $^{3+}$ :CaWO $_4$ at milliKelvin temperaturesPhonon-bottlenecked spin relaxation of Er$^{3+}$:CaWO$_4$ at milliKelvin temperatures

S. Rajendran, B. Mistri, P. K. Sharma +5 more

We study spin-lattice relaxation times of electron spins in Er $^{3+}$ :CaWO $_4$ at millikelvin temperature, detected via their coupling to a low-mode volume superconducting resonator. At large magnetic field supporting strong phonon-emission rates, we observe a noticeable increase in relaxation times with increasing spin-excitations, which exhibit a unique $[\tanh (\hbar ω_0/k_\text{B} T)]^2$ temperature dependence. These observations are typical of a phonon-bottlenecked spin relaxation, and have implications for quantum technologies that exploit rare-earth spin ensembles as coherent resources.We study spin-lattice relaxation times of electron spins in Er$^{3+}$:CaWO$_4$ at millikelvin temperature, detected via their coupling to a low-mode volume superconducting resonator. At large magnetic field supporting strong phonon-emission rates, we observe a noticeable increase in relaxation times with increasing spin-excitations, which exhibit a unique $[\tanh (\hbar ω_0/k_\text{B} T)]^2$ temperature dependence. These observations are typical of a phonon-bottlenecked spin relaxation, and have implications for quantum technologies that exploit rare-earth spin ensembles as coherent resources.

quant-pharXiv:2605.18208May 19, 20260 citations

Week-long-lifetime microwave spectral holes in an erbium-doped scheelite crystal at millikelvin temperature

Zhiren Wang, Sen Lin, Marianne Le Dantec +9 more

Rare-earth-ions (REI) doped crystals have remarkable optical and spin properties characterized by narrow homogeneous linewidths, which can be studied despite the large inhomogeneous broadening of the ensemble line through spectral hole burning (SHB). Here, we report SHB spectroscopic measurements in a scheelite crystal of CaWO4 by pumping the spin transition of a paramagnetic REI (Er3+) at microwave frequency and millikelvin temperatures, with nuclear spin states of neighboring 183W atoms serving as the auxiliary levels. The repeated application of pairs of microwave pulses generates a periodic modulation of the Er3+ density profile, which we observe spectrally and in the time-domain as an accumulated echo. The lifetime of the holes and accumulated echoes rises steeply as the sample temperature is decreased, exceeding a week at 10mK. Our results demonstrate that millikelvin temperatures can be beneficial for signal processing applications requiring long spectral hole lifetimes. The authors report spectral hole burning with a record hole lifetime in a Er3+ doped scheelite crystal CaWO4 at mK temperatures. This can benefit applications in classical and quantum information processing.Rare-earth-ions (REI) doped crystals have remarkable optical and spin properties characterized by narrow homogeneous linewidths, which can be studied despite the large inhomogeneous broadening of the ensemble line through spectral hole burning (SHB). Here, we report SHB spectroscopic measurements in a scheelite crystal of CaWO4 by pumping the spin transition of a paramagnetic REI (Er3+) at microwave frequency and millikelvin temperatures, with nuclear spin states of neighboring 183W atoms serving as the auxiliary levels. The repeated application of pairs of microwave pulses generates a periodic modulation of the Er3+ density profile, which we observe spectrally and in the time-domain as an accumulated echo. The lifetime of the holes and accumulated echoes rises steeply as the sample temperature is decreased, exceeding a week at 10mK. Our results demonstrate that millikelvin temperatures can be beneficial for signal processing applications requiring long spectral hole lifetimes. The authors report spectral hole burning with a record hole lifetime in a Er3+ doped scheelite crystal CaWO4 at mK temperatures. This can benefit applications in classical and quantum information processing.

Nature CommunicationsOct 10, 20254 citations

Magnetic Trapping of Neutral Atoms

Harold J. Metcalf, P. van der Straten

Graduate texts in contemporary physicsJan 1, 19993 citations

Narrow-Line Magneto-Optical Cooling and Trapping of Strongly Magnetic Atoms

Andrew J. Berglund, James L. Hanssen, Jabez J. McClelland

Laser cooling on weak transitions is a useful technique for reaching ultracold temperatures in atoms with multiple valence electrons. However, for strongly magnetic atoms a conventional narrow-line magneto-optical trap (MOT) is destabilized by competition between optical and magnetic forces. We overcome this difficulty in Er by developing an unusual narrow-line MOT that balances optical and magnetic forces using laser light tuned to the blue side of a narrow (8 kHz) transition. The trap population is spin polarized with temperatures reaching below 2 muK. Our results constitute an alternative method for laser cooling on weak transitions, applicable to rare-earth-metal and metastable alkaline earth elements.Laser cooling on weak transitions is a useful technique for reaching ultracold temperatures in atoms with multiple valence electrons. However, for strongly magnetic atoms a conventional narrow-line magneto-optical trap (MOT) is destabilized by competition between optical and magnetic forces. We overcome this difficulty in Er by developing an unusual narrow-line MOT that balances optical and magnetic forces using laser light tuned to the blue side of a narrow (8 kHz) transition. The trap population is spin polarized with temperatures reaching below 2 muK. Our results constitute an alternative method for laser cooling on weak transitions, applicable to rare-earth-metal and metastable alkaline earth elements.

arXiv:0802.0857Physical Review LettersMar 18, 200865 citations

Phonon-bottlenecked spin relaxation of Er

^{3+}

:CaWO

_4

at milliKelvin temperatures

We study spin-lattice relaxation times of electron spins in Er

^{3+}

:CaWO

_4

at millikelvin temperature, detected via their coupling to a low-mode volume superconducting resonator. At large magnetic field supporting strong phonon-emission rates, we observe a noticeable increase in relaxation times with increasing spin-excitations, which exhibit a unique

[\tanh (\hbar ω_0/k_\text{B} T)]^2

temperature dependence. These observations are typical of a phonon-bottlenecked spin relaxation, and have implications for quantum technologies that exploit rare-earth spin ensembles as coherent resources.