Universal unitary gate for single-photon spin-orbit four-dimensional states (original) (raw)
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Quantum Information Transfer from Spin to Orbital Angular Momentum of Photons
Physical Review Letters, 2009
The optical "spin-orbit" coupling occurring in a suitably patterned nonuniform birefringent plate known as 'q-plate' allows entangling the polarization of a single photon with its orbital angular momentum (OAM). This process, in turn, can be exploited for building a bidirectional "spin-OAM interface", capable of transposing the quantum information from the spin to the OAM degree of freedom of photons and vice versa. Here, we experimentally demonstrate this process by singlephoton quantum tomographic analysis. Moreover, we show that two-photon quantum correlations such as those resulting from coalescence interference can be successfully transferred into the OAM degree of freedom.
General U (4) gate for photon polarization and orbital angular momentum
2010
We examine the implementation of an arbitrary U(4) gate consisting of CNOT gates and single qubit unitary gates for the Hilbert space of photon spin polarization and two states of photon orbital angular momentum. Our scheme improves over a recently proposed one that uses q-plates because the fidelity is limited only by losses thus in principle it could be used to achieve a perfect transformation. * Electronic address: craig.hamilton@fjfi.cvut.cz
Polarization control of single photon quantum orbital angular momentum states
Optics Express, 2009
The orbital angular momentum of photons, being defined in an infinitely dimensional discrete Hilbert space, offers a promising resource for high-dimensional quantum information protocols in quantum optics. The biggest obstacle to its wider use is presently represented by the limited set of tools available for its control and manipulation. Here, we introduce and test experimentally a series of simple optical schemes for the coherent transfer of quantum information from the polarization to the orbital angular momentum of single photons and vice versa. All our schemes exploit a newly developed optical device, the so-called "q-plate", which enables the manipulation of the photon orbital angular momentum driven by the polarization degree of freedom. By stacking several qplates in a suitable sequence, one can also access to higher-order angular momentum subspaces. In particular, we demonstrate the control of the orbital angular momentum m degree of freedom within the subspaces of |m| = 2h and |m| = 4h per photon. Our experiments prove that these schemes are reliable, efficient and have a high fidelity.
Deterministic qubit transfer between orbital and spin angular momentum of single photons
Optics Letters, 2012
In this work we experimentally implement a deterministic transfer of a generic qubit initially encoded in the orbital angular momentum of a single photon to its polarization. Such transfer of quantum information, completely reversible, has been implemented adopting a electrically tunable q-plate device and a Sagnac interferomenter with a Dove's prism. The adopted scheme exhibits a high fidelity and low losses.
Quantum information processing with spin-orbit laser modes
Spintronics VI, 2013
Optical vortices are employed for quantum information encoding, where the wave front structure combined to the polarization vector of an optical beam can be regarded as a spin-orbit realization of a two-qubit system. We will discuss quantum information protocols that can be implemented in these degrees of freedom.
Single-photon two-qubit SWAP gate for entanglement manipulation
Physical Review A, 2005
A SWAP operation between different types of qubits of single photons is essential for manipulating hyperentangled photons for a variety of applications. We have implemented an efficient SWAP gate for the momentum and polarization degrees of freedom of single photons. The SWAP gate was utilized in a single-photon two-qubit quantum logic circuit to deterministically transfer momentum entanglement between a pair of down-converted photons to polarization entanglement. The polarization entanglement thus obtained violates Bell's inequality by more than 150 standard deviations.
Single-Photon Two-Qubit Logic Gates
2004
We present experimental results of deterministic linear optical Controlled-NOT and SWAP gates for single-photon two-qubit quantum logic. In our implementation one qubit is encoded in the polarization degree of freedom of the photon and the other is encoded in the momentum. Momentum-and polarization-controlled NOT gates are demonstrated. They are then combined to form a SWAP gate to convert pairs of momentum-entangled photons into polarization-entangled photons.
Nature Communications, 2014
Photonics has become a mature field of quantum information science, where integrated optical circuits offer a way to scale the complexity of the setup as well as the dimensionality of the quantum state. On photonic chips, paths are the natural way to encode information. To distribute those high-dimensional quantum states over large distances, transverse spatial modes, like orbital angular momentum possessing Laguerre Gauss modes, are favourable as flying information carriers. Here we demonstrate a quantum interface between these two vibrant photonic fields. We create three-dimensional path entanglement between two photons in a nonlinear crystal and use a mode sorter as the quantum interface to transfer the entanglement to the orbital angular momentum degree of freedom. Thus our results show a flexible way to create high-dimensional spatial mode entanglement. Moreover, they pave the way to implement broad complex quantum networks where high-dimensionally entangled states could be distributed over distant photonic chips.
Spintronic single-qubit gate based on a quantum ring with spin-orbit interaction
Physical Review B, 2005
In a quantum ring connected with two external leads the spin properties of an incoming electron are modified by the spin-orbit interaction resulting in a transformation of the qubit state carried by the spin. The ring acts as a one qubit spintronic quantum gate whose properties can be varied by tuning the Rashba parameter of the spin-orbit interaction, by changing the relative position of the junctions, as well as by the size of the ring. We show that a large class of unitary transformations can be attained with already one ring -or a few rings in series -including the important cases of the Z, X, and Hadamard gates. By choosing appropriate parameters the spin transformations can be made unitary, which corresponds to lossless gates. PACS numbers: 03.67.-a, 71.70.Ej, 85.35.Ds
Physical Review B, 2008
We propose a quantum nondemolition method-a giant optical Faraday rotation near the resonant regime to measure a single-electron spin in a quantum dot inside a microcavity where a negatively charged exciton strongly couples to the cavity mode. Left-circularly and right-circularly polarized lights reflected from the cavity obtain different phase shifts due to cavity quantum electrodynamics and the optical spin selection rule. This yields giant and tunable Faraday rotation that can be easily detected experimentally. Based on this spin-detection technique, a deterministic photon-spin entangling gate and a scalable scheme to create remote spin entanglement via a single photon are proposed.