Demonstration of the reduction of decoherent errors in a solid-state qubit using dynamic decoupling techniques

We experimentally demonstrate that decoherent errors for a qubit can be reduced using dynamic decoupling control. The quantum system in our experiment is a praseodymium ground-state hyperfine transition in Pr3+: Y2 SiO5. These experiments were undertake

Generation of Light with Multimode Time-Delayed Entanglement Using Storage in a Solid-State Spin-Wave Quantum Memory

Here, we demonstrate generating and storing entanglement in a solid-state spin-wave quantum memory with on-demand readout using the process of rephased amplified spontaneous emission (RASE). Amplified spontaneous emission (ASE), resulting from an inverted ensemble of Pr^3+ions doped into a Y2 SiO5 crystal, generates entanglement between collective states of the praseodymium ensemble and the output light. The ensemble is then rephased using a four-level photon echo technique. Entanglement between the ASE and its echo is confirmed and the inseparability violation preserved when the RASE is stored as a spin wave for up to 5 μs. RASE is shown to be temporally multimode with almost perfect distinguishability between two temporal modes demonstrated. These results pave the way for the use of multimode solid-state quantum memories in scalable quantum networks

Microwave to optical photon conversion via fully concentrated rare-earth-ion crystals

Most investigations of rare-earth ions in solids for quantum information have used crystals where the rare-earth ion is a dopant. Here, we analyze the conversion of quantum information from microwave photons to optical frequencies using crystals where the rare-earth ions, rather than being dopants, are part of the host crystal. These concentrated crystals are attractive for frequency conversion because of their large ion densities and small linewidths. We show that conversion with both high efficiency and large bandwidth is possible in these crystals. In fact, the collective coupling between the rare-earth ions and the optical and microwave cavities is large enough that the limitation on the bandwidth of the devices will instead be the spacing between magnon modes in the crystal

Efficient quantum memory for light

Storing and retrieving a quantum state of light on demand, without corrupting the information it carries, is an important challenge in the field of quantum information processing. Classical measurement and reconstruction strategies for storing light mus

High efficiency gradient echo memory with 3-level atoms

We present experimental results demonstrating 87% efficiency for single pulse recall, and storage of up to 20 pulses using a three level gradient echo memory with hot rubidium vapour as the storage medium. We also present results showing pulse resequencing, as well as pulse splitting and spectral manipulation. The decoherence mechanisms affecting the system, in particular scattering due to the control field and how it can be minimised by turning the control field off during storage, are also discussed

Toward quantum microwave to optical conversion using rare earth ion containing crystals

With an Er:Y2SiO5 crystal at 4 K we achieve microwave to optical conversion with quantum efficiency 10-5. Theory and initial results at milli-kelvin temperatures and with fully concentrated rare earth crystals point to significant improvements