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Hybrid Toffoli gate on photons and quantum spins.

Luo MX, Ma SY, Chen XB, Wang X - Sci Rep (2015)

Bottom Line: We present implementations of a key quantum circuit: the three-qubit Toffoli gate.The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom.Our results show that photons and quantum spins may be used alternatively in quantum information processing.

View Article: PubMed Central - PubMed

Affiliation: Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China.

ABSTRACT
Quantum computation offers potential advantages in solving a number of interesting and difficult problems. Several controlled logic gates, the elemental building blocks of quantum computer, have been realized with various physical systems. A general technique was recently proposed that significantly reduces the realization complexity of multiple-control logic gates by harnessing multi-level information carriers. We present implementations of a key quantum circuit: the three-qubit Toffoli gate. By exploring the optical selection rules of one-sided optical microcavities, a Toffoli gate may be realized on all combinations of photon and quantum spins in the QD-cavity. The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom. Our results show that photons and quantum spins may be used alternatively in quantum information processing.

No MeSH data available.


Schematic energy level and optical selection rules due to Pauli’s exclusion principle. and  are the input and output field operators of the waveguide, respectively.  and  represent the left circularly and right circularly polarized photons, respectively.   and  represent the spins of the excess electron.   and  represent the negatively charged exciton X−1.
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f1: Schematic energy level and optical selection rules due to Pauli’s exclusion principle. and are the input and output field operators of the waveguide, respectively. and represent the left circularly and right circularly polarized photons, respectively.  and represent the spins of the excess electron.  and represent the negatively charged exciton X−1.

Mentions: Consider a singly charged GaAs/InAs quantum dot (QD) inside a micropillar cavity373839, which consists of a λ-cavity between two GaAs/Al(Ga)As distributed Bragg reflectors. The QD is located in the center of the cavity to achieve maximal light-matter coupling. If the QD is neutral, optical excitation generates a neutral exciton. If the QD is singly charged, i.e., a single excess electron is injected, optical excitation can create a negatively-charged exciton (X−), which consists of two electrons bound to one hole373839. Due to Pauli’s exclusion principle, for the spin state , X− in the state with the two electron spins antiparallel is created by resonantly absorbing a left circularly polarized photon , where the heavy-hole spin state ; for the spin state , X− in the state with the two electron spins antiparallel is created by resonantly absorbing a right circularly polarization photon , where heavy-hole spin state , as shown in Fig. 1. In the limit of a weak incoming field404142, the spin cavity system behaves like a beam splitter. Based on the transmission and reflection rules of the cavity for an incident circular polarization photon conditioned on the QD-spin state, the dynamics of the interaction between the photon and spin in a QD-microcavity coupled system is described as below3233434445


Hybrid Toffoli gate on photons and quantum spins.

Luo MX, Ma SY, Chen XB, Wang X - Sci Rep (2015)

Schematic energy level and optical selection rules due to Pauli’s exclusion principle. and  are the input and output field operators of the waveguide, respectively.  and  represent the left circularly and right circularly polarized photons, respectively.   and  represent the spins of the excess electron.   and  represent the negatively charged exciton X−1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644947&req=5

f1: Schematic energy level and optical selection rules due to Pauli’s exclusion principle. and are the input and output field operators of the waveguide, respectively. and represent the left circularly and right circularly polarized photons, respectively.  and represent the spins of the excess electron.  and represent the negatively charged exciton X−1.
Mentions: Consider a singly charged GaAs/InAs quantum dot (QD) inside a micropillar cavity373839, which consists of a λ-cavity between two GaAs/Al(Ga)As distributed Bragg reflectors. The QD is located in the center of the cavity to achieve maximal light-matter coupling. If the QD is neutral, optical excitation generates a neutral exciton. If the QD is singly charged, i.e., a single excess electron is injected, optical excitation can create a negatively-charged exciton (X−), which consists of two electrons bound to one hole373839. Due to Pauli’s exclusion principle, for the spin state , X− in the state with the two electron spins antiparallel is created by resonantly absorbing a left circularly polarized photon , where the heavy-hole spin state ; for the spin state , X− in the state with the two electron spins antiparallel is created by resonantly absorbing a right circularly polarization photon , where heavy-hole spin state , as shown in Fig. 1. In the limit of a weak incoming field404142, the spin cavity system behaves like a beam splitter. Based on the transmission and reflection rules of the cavity for an incident circular polarization photon conditioned on the QD-spin state, the dynamics of the interaction between the photon and spin in a QD-microcavity coupled system is described as below3233434445

Bottom Line: We present implementations of a key quantum circuit: the three-qubit Toffoli gate.The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom.Our results show that photons and quantum spins may be used alternatively in quantum information processing.

View Article: PubMed Central - PubMed

Affiliation: Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China.

ABSTRACT
Quantum computation offers potential advantages in solving a number of interesting and difficult problems. Several controlled logic gates, the elemental building blocks of quantum computer, have been realized with various physical systems. A general technique was recently proposed that significantly reduces the realization complexity of multiple-control logic gates by harnessing multi-level information carriers. We present implementations of a key quantum circuit: the three-qubit Toffoli gate. By exploring the optical selection rules of one-sided optical microcavities, a Toffoli gate may be realized on all combinations of photon and quantum spins in the QD-cavity. The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom. Our results show that photons and quantum spins may be used alternatively in quantum information processing.

No MeSH data available.