Optical Spin-Wave Storage in a Solid-State Hybridized Electron-Nuclear Spin Ensemble.

Solid-state impurity spins with optical control are currently investigated for quantum networks and repeaters. Among these, rare-earth-ion doped crystals are promising as quantum memories for light, with potentially long storage time, high multimode capacity, and high bandwidth. However, with spins there is often a tradeoff between bandwidth, which favors electronic spin, and memory time, which favors nuclear spins. Here, we present optical storage experiments using highly hybridized electron-nuclear hyperfine states in ^{171}Yb^{3+}:Y_{2}SiO_{5}, where the hybridization can potentially offer both long storage time and high bandwidth. We reach a storage time of 1.2 ms and an optical storage bandwidth of 10 MHz that is currently only limited by the Rabi frequency of the optical control pulses. The memory efficiency in this proof-of-principle demonstration was about 3%. The experiment constitutes the first optical storage using spin states in any rare-earth ion with electronic spin. These results pave the way for rare-earth based quantum memories with high bandwidth, long storage time, and high multimode capacity, a key resource for quantum repeaters.

Families living with parental mental illness and their experiences of family interventions.

WHAT IS KNOWN ON THE SUBJECT?: Coping with parental mental illness in families can be challenging for both children and parents. Providing evidence-based family interventions to families where a parent has a mental illness can enhance the relationships in the family. Although psychiatric research has shown that evidence-based family interventions may improve the communication and understanding of parental mental illness, there is a lack in this area of research from an everyday clinical context. WHAT DOES THIS PAPER ADD TO EXISTING KNOWLEDGE?: Our study reinforces the fact that parents with mental illnesses are searching for support from psychiatric services in order to talk to their children about their illness. The finding that under-age children comply when they are told by their parents to join an intervention in psychiatric services supporting the family is something not observed earlier in research. This study once more illuminates the fact that partners of a person with parental mental illness are seldom, in an obvious way, included in family support interventions. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Psychiatric services, and especially mental health nurses, have an important task in providing families with parental mental illness with support concerning communication with their children and in including the "healthy" partner in family support interventions. ABSTRACT: Introduction Although research has shown that evidence-based family interventions in research settings improve the communication and understanding of parental mental illness, there is a lack of knowledge about interventions in an everyday clinical context. Aim This study explores how families with parental mental illness experience family interventions in a natural clinical context in psychiatric services. Method Five families with children aged 10-12 were recruited from psychiatric services in southern Sweden and interviewed in a manner inspired by naturalistic inquiry and content analysis. Both family and individual interviews were performed. Results In striving to lead an ordinary life while coping with the parental mental illness, these families sought the support of the psychiatric services, especially in order to inform their children about the mental illness. Despite different family interventions, the family members felt supported and reported that the number of conflicts in the family had decreased. The parents were appreciative of help with child-rearing questions, and the children experienced a calmer family atmosphere. However, the partner of the person with mental illness experienced being left without support. Implications for practice Our study shows that psychiatric services, and especially mental health nurses, are in a position to more regularly offer family interventions in supporting the children and the healthy partners.

Interference of multimode photon echoes generated in spatially separated solid-state atomic ensembles.

High-visibility interference of photon echoes generated in spatially separated solid-state atomic ensembles is demonstrated. The solid-state ensembles were LiNbO(3) waveguides doped with erbium ions absorbing at 1.53 microm. Bright coherent states of light in several temporal modes (up to 3) are stored and retrieved from the optical memories using two-pulse photon echoes. The stored and retrieved optical pulses, when combined at a beam splitter, show almost perfect interference, which demonstrates both phase preserving storage and indistinguishability of photon echoes from separate optical memories. By measuring interference fringes for different storage times, we also show explicitly that the visibility is not limited by atomic decoherence. These results are relevant for novel quantum-repeater architectures with photon-echo based multimode quantum memories.

Fidelity of an optical memory based on stimulated photon echoes.

We investigated the preservation of information encoded into the relative phase and amplitudes of optical pulses during storage and retrieval in an optical memory based on stimulated photon echo. By interfering photon echoes produced in a single-mode Ti:Er:LiNbO(3) waveguide, we found that decoherence in the medium translates only as loss and not as degradation of information. We measured a visibility for interfering echoes close to 100%. These results may have important implications for future long-distance quantum communication protocols.

Coherent transient data-rate conversion and data transformation.

Temporal compressions of optical pulses and pulse trains have been performed by the photon-echo process in Tm-doped YAG at 793 nm. Single-pulse temporal compression by almost a factor of 500 from 10 micros to 22 ns and pulse train compression by a factor of 14 from 5micros to 350 ns with a high-speed frequency-tunable external-cavity diode laser are demonstrated. It is suspected that significantly higher compression could be obtained by improved control of the laser frequency and laser frequency chirps. Theoretically, Tm-doped YAG should be capable of compressing single pulses by almost a factor of 10(7).