72 research outputs found
Revealing inherent quantum interference and entanglement of a Dirac Fermion
The Dirac equation is critical to understanding the universe, and plays an
important role in technological advancements. Compared to the stationary
solution, the dynamical evolution under the Dirac Hamiltonian is less
understood, exemplified by Zitterbewegung. Although originally predicted in
relativistic quantum mechanics, Zitterbewegung can also appear in some
classical systems, which leads to the important question of whether
Zitterbewegung of Dirac Fermions is underlain by a more fundamental and
universal interference behavior without classical analogs. We here reveal such
an interference pattern in phase space, which underlies but goes beyond
Zitterbewegung, and whose nonclassicality is manifested by the negativity of
the phase-space quasiprobability distribution, and the associated
pseudospin-momentum entanglement. We confirm this discovery by numerical
simulation and an on-chip experiment, where a superconducting qubit and a
quantized microwave field respectively emulate the internal and external
degrees of freedom of a Dirac particle. The measured quasiprobability
negativities well agree with the numerical simulation. Besides being of
fundamental importance, the demonstrated nonclassical effects are useful in
quantum technology.Comment: 18 pages, 15 figure
In situ synthesis of natural rubber latex-supported gold nanoparticles for flexible SERS substrates
Natural rubber latex (NRL) from Hevea brasiliensis was used as a matrix to synthesize gold nanoparticles (AuNPs), leading to an organic-inorganic hybrid latex of NRL-supported AuNPs (AuNPs@NRL). The in situ and environmentally friendly preparation of AuNPs in an NRL matrix was developed by thermal treatment without using any other reducing agents or stabilizers because natural rubber particles and non-rubber components present in serum can serve as supporters for the synthesized AuNPs. As a result, the nanosized and well-dispersed AuNPs not only are decorated on the surface of natural rubber particles, but also can be found in the serum of NRL. The size of the AuNPs presented in NRL matrix can be controlled by adjusting the concentration of NRL. Furthermore, the flexible surface-enhanced Raman scattering (SERS) substrates made from the AuNPs@NRL through vacuum filtration presented good enhancement of the Raman probe molecule of 4-mercaptopyridine and outstanding SERS reproducibility. The capability of synthesizing the bio-supported nanohybrid latex provides a novel green and simple approach for the fabrication of flexible and effective SERS substrates
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