REID memory

Project to run with Astana in Kazan. We are planning to repeat an experiment published here PRL, 111, 033601 (2013).

Novelty

• We would like to use original decoupling scheme,
• We would like to combine long lifetime by german group with Saboony high effi
• Increase T1 by using lower temperatures

Quick overview

The group is using Pr3+:Y2SiO5, it has long population lifetimes (T1~100s).

• Coils produce 250 G,
• crystal is at 3 K, 3mm long, doping 0.05%
• wavelength $\lambda$=606 nm

Necessary equipment

Superconducting Helmholtz coils

In this paper they write next

Two coils (diameter of 5 mm, five windings each), placed inside the cryostat around the crystal, are driven by amplified signals 
from an arbitrary waveform generator (AWG)  to generate the required rf pulses. The maximum rf power is  Prf = 10 W. Three pairs 
of superconducting coils in orthogonal Helmholtz configuration, with diameters of a few  centimeters, also placed in the cryostat
around the crystal, serve to provide static magnetic fields of variable strength and  direction in the crystal. With 200–400 
windings on each coil and at a current of 10 A, we reach maximal magnetic fields of about 2000 G in each spatial direction. The 
coils are driven by high-power operational amplifiers (Servowatt DCP 390/20) which act as four-quadrant power supplies. On time 
scales of 100 ms we measured a relative fluctuation of the static magnetic-field strength of well below 10−4. The long-term drift 
of the magnetic field over several hours was below 1 G.

In Heinze's thesis he mentions important considerations to make:

• For the whole coil assembly he used an oxygen-free copper covered with 0.2 um gold layer.
• This geometry has the lowest mutual inductance of RF and static coils.
• Furthermore, the entire system has been provided with a continuous ? in order to prevent HF-induced eddy currents.

He uses two sets of coils for high (up to 2000 G) and low (<200 G) fields. He claims that 20-40 turns ensures good setting accuracy Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): B=\mu_0\frac{8}{\sqrt {125}} \frac{N \Delta I}{r}

and adds that in this case electronic noise or fluctuations in the current intensity has only a very weak effect on the generated magnetic field.

Laser system

Stabilize laser? Narrow the line +-5V <->20GHz, modulation only with a cavity.

Stages of experiment

optimization of ZEFOZ point

Consists of two experiments:

• Raman heterodyne spectroscopy
• Spin-echo

Contacts

laboratory