Quantum memories could benefit many devices in quantum information processing. For a quantum to be useful in real-world applications, the quantum memory must have a high recall efficiency.Here we demonstrate an efficient (up to 80%) spin-storage quantum memory in 167 Er 3+ :Y2SiO5, using the 4-level rephased amplified spontaneous emission protocol. We show non-classical correlations between the ASE and RASE fields produced by the quantum memory. Also, we demonstrate the storage of 70 temporal modes, with a write time of 150 µs, and a storage time of 25 µs. Finally, a clear pathway is presented to improve the efficiency, storage time, and mode capacity. Such a device would have applications in quantum networking and measurement-based quantum computing.

A 3D printer was developed for the 3D printing of cellulose hydrogels using open source software and simple 3D printer hardware. Using a temperature-based sol-gel transition of cellulose dissolved in aqueous solutions of sodium hydroxide (NaOH) and urea, a three-dimensional gel can be created by moving a focused laser beam across a bath of the cellulose solution and lowering the print stage after every layer. A line width of 100-150 µm and layer thickness of 25 µm of the printed part could be achieved. No delamination between printed layers occurred and no additional support material was needed to create free hanging structures due to suspending the printed part in printing liquid. By adding cellulose powder to the solution, the gelation temperature, the gel strength and stiffness can be manipulated while maintaining a high internal porosity of the gel. A laser power of 100 mW was found to produce the highest quality print with an accurate representation of the previously designed part. Lower power settings (80 mW) produced insufficient gelation and as a result reduced print accuracy while higher power settings (120 mW) caused the gel to burn.

We demonstrate a simple design for an in-fibre Fabry-Perot interferometer (FPI) equivalent, constructed by splicing together two ports of a 99:1 in-fibre beamsplitter to form a fibre ring resonator (FRR). A Peltier device is used to heat a length of the fibre, which scans the resonant frequency of the FPI in a controllable manner primarily by changing the refractive index of the fibre. This allows the device to be employed in applications where a standard Fabry-Perot cavity is used, in this case for laser mode monitoring. Our FRR has a measured finesse of 123(2) and is shown to be stable over long time periods. This provides an inexpensive and simple solution for applications with low performance requirements, and with relatively minor upgrades could be used for more exacting applications such as frequency locking.