Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMolecule-based coherent light-spin interfaces for quantum information processing -- optical spin state polarization in a binuclear Europium complex
102
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ions (REIs) are suitable candidates for QIP protocols due to their extraordinary photo-physical and magnetic quantum properties such as long optical and spin coherence lifetimes ($T_2$). However, molecules incorporating REIs, despite having advantageous properties such as atomically exact quantum tunability, inherent scalability, and large portability, have not yet been studied for QIP applications. As a first testimony of the usefulness of REI molecules for optical QIP applications, we demonstrate in this study that narrow spectral holes can be burned in the inhomogeneously broadened $^5$D$_0to^7$F$_0$ optical transition of a binuclear Eu(III) complex, rendering a homogeneous linewidth ($Gamma_h$) = 22 $pm$ 1 MHz, which translates as $T_2 = 14.5$ $pm$ 0.7 ns at 1.4 K. Moreover, long-lived spectral holes are observed, demonstrating efficient polarization of Eu(III) ground state nuclear spins, a fundamental requirement for all-optical spin initialization and addressing. These results elucidate the usefulness of REI-based molecular complexes as versatile coherent light-spin interfaces for applications in quantum communications and processing.
rate research
Read More
Waveguide-based spin-photon interfaces on the GaAs platform have emerged as a promising system for a variety of quantum information applications directly integrated into planar photonic circuits. The coherent control of spin states in a quantum dot can be achieved by applying circularly polarized laser pulses that may be coupled into the planar waveguide vertically through radiation modes. However, proper control of the laser polarization is challenging since the polarization is modified through the transformation from the far field to the exact position of the quantum dot in the nanostructure. Here we demonstrate polarization-controlled excitation of a quantum-dot electron spin and use that to perform coherent control in a Ramsey interferometry experiment. The Ramsey interference reveals a pure dephasing time of $ 2.2pm0.1 $ ns, which is comparable to the values so far only obtained in bulk media. We analyze the experimental limitations in spin initialization fidelity and Ramsey contrast and identify the underlying mechanisms.
We have developed semiconductor point contact devices in which nuclear spins in a nanoscale region are coherently controlled by all-electrical methods. Different from the standard nuclear-magnetic resonance technique, the longitudinal magnetization of nuclear spins is directly detected by measuring resistance, resulting in ultra-sensitive detection of the microscopic quantity of nuclear spins. All possible coherent oscillations have been successfully demonstrated between two levels from four nuclear spin states of I = 3/2 nuclei. Quantum information processing is discussed based on two fictitious qubits of an I = 3/2 system and methods are described for performing arbitrary logical gates both on one and two qubits. A scheme for quantum state tomography based on Mz-detection is also proposed. As the starting point of quantum manipulations, we have experimentally prepared the effective pure states for the I = 3/2 nuclear spin system.
Quantum light-matter interfaces (QLMIs) connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching, and studies of fundamental physics. Rare-earth-ion (REI) doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium REIs to photonic nano-cavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2-4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled REIs is performed via photon echoes. Long optical coherence times (T2~100 microseconds) and small inhomogeneous broadening are measured for the cavity-coupled REIs, thus demonstrating their potential for on-chip scalable QLMIs.
Previously a new scheme of quantum information processing based on spin coherent states of two component Bose-Einstein condensates was proposed (Byrnes {it et al.} Phys. Rev. A 85, 40306(R)). In this paper we give a more detailed exposition of the scheme, expanding on several aspects that were not discussed in full previously. The basic concept of the scheme is that spin coherent states are used instead of qubits to encode qubit information, and manipulated using collective spin operators. The scheme goes beyond the continuous variable regime such that the full space of the Bloch sphere is used. We construct a general framework for quantum algorithms to be executed using multiple spin coherent states, which are individually controlled. We illustrate the scheme by applications to quantum information protocols, and discuss possible experimental implementations. Decoherence effects are analyzed under both general conditions and for the experimental implementation proposed.
The spin of an electron in a self-assembled InAs/GaAs quantum dot molecule is optically prepared and measured through the trion triplet states. A longitudinal magnetic field is used to tune two of the trion states into resonance, forming a superposition state through asymmetric spin exchange. As a result, spin-flip Raman transitions can be used for optical spin initialization, while separate trion states enable cycling transitions for non-destructive measurement. With two-laser transmission spectroscopy we demonstrate both operations simultaneously, something not previously accomplished in a single quantum dot.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
