![]() Electron Paramagnetic Resonance of Transition Metal Ions Ch. Hyperfine interaction of Er 3+ ions in Y2SiO5: an electron paramagnetic resonance spectroscopy study. EPR and spin-lattice relaxation of rare-earth activated centres in Y2SiO5 single crystals. Effects of magnetic field orientation on optical decoherence in Er 3+ : Y2SiO5. Quantum repeaters with imperfect memories: cost and scalability. Large efficiency at telecom wavelength for optical quantum memories. Electro-optic quantum memory for light using two-level atoms. Telecommunication-wavelength solid-state memory at the single photon level. Temperature and concentration dependence of optical dephasing, spectral-hole lifetime, and anisotropic absorption in Eu 3+ : Y2SiO5. Spectral hole burning and holography in an Pr 3+ : Y2SiO5 crystal. Mapping multiple photonic qubits into and out of one solid-state atomic ensemble. Usmani, I., Afzelius, M., de Riedmatten, H. Zeeman-level lifetimes in Er 3+ : Y2SiO5. Identification of Λ-like systems in Er 3+ : Y2SiO5 and observation of electromagnetically induced transparency. Optically addressable nuclear spins in a solid with a six-hour coherence time. Efficient quantum memory using a weakly absorbing sample. Multiplexed on-demand storage of polarization qubits in a crystal. Solid state spin-wave quantum memory for time-bin qubits. Coherent spin control at the quantum level in an ensemble-based optical memory. Generation of light with multimode time-delayed entanglement using storage in a solid-state spin-wave quantum memory. Storing a single photon as a spin wave entangled with a flying photon in the telecommunication bandwidth. Quantum teleportation from a telecom-wavelength photon to a solid-state quantum memory. Quantum storage of photonic entanglement in a crystal. Broadband waveguide quantum memory for entangled photons. Quantum correlations between single telecom photons and a multimode on-demand solid-state quantum memory. Storage of up-converted telecom photons in a doped crystal. A waveguide frequency converter connecting rubidium based quantum memories to the telecom C-band. Entanglement of light-shift compensated atomic spin waves with telecom light. A quantum memory with telecom-wavelength conversion. Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre. Non-classical correlations between single photons and phonons from a mechanical oscillator. Long-distance quantum communication with atomic ensembles and linear optics. With an absorption of 70 dB cm −1 at 1,538 nm and Λ transitions enabling spin-wave storage, this material is the first candidate identified for an efficient, broadband quantum memory at telecommunication wavelengths. We also demonstrate efficient spin pumping of the entire ensemble into a single hyperfine state, a requirement for broadband spin-wave storage. We observe a hyperfine coherence time of 1.3 s. Here we describe the spin dynamics of 167Er 3+: Y 2SiO 5 in a high magnetic field and demonstrate that this material has the characteristics for a practical quantum memory in the 1,550 nm communication band. Due to a lack of a suitable storage material, a quantum memory that operates in the 1,550 nm optical fibre communication band with a storage time greater than 1 μs has not been demonstrated. For networks, the quantum coherence times of these transitions must be long compared to the network transmission times, approximately 100 ms for a global communication network. These memories operate by reversibly mapping the quantum state of light onto the quantum transitions of a material system. c) What are the limits of v as a function of τ L ( t ) in order for the input-output relation of the wireless channel to be expressed as y = h x, ∀ m = 1, …, M, where h is constant ∀ m.Quantum memories for light will be essential elements in future long-range quantum communication networks. a) What is the duration of the packet? b) What are the limits of T S in order for the input-output relation of the wireless channel to be expressed as y = h x, ∀ m = 1, …, M. Assume that τ S ( t ) = 0 Assume that you have a packet comprised of M symbols, where the time distance between two neighboring symbols is T S . The coherence bandwidth, can be computed as W c = 2 1 ∣ τ L ( t ) − τ S ( t ) ∣ 1 , where τ L ( t ) and τ S ( t ) represent the longest and shortest delays, respectively, where a delay is the time required for the signal to arrive from Tx to Rx via a given path. The coherence time of a wireless channel can be computed as T c = 4 1 2 f c v c , where c is the speed of light, f c is the carrier frequency, and v is the maximum possible speed between the Tx and Rx. ![]()
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