Shaping the Spatial Coherence of Quantum Source

There has been immense research interest in quantum entanglement due to its ability to generate stronger-thanclassical nonlocal correlations.^([1,2])These strong,nonlocal correlations form the backbone of various quantum information protocols.One of the core principles of quantum entanglement is quantum coherence,which provides deep insights into the statistical correlations among quantum particles.^([3–5])Quantum coherence reflects the wavelike properties of quantum particles,enabling them to exhibit interference and unique quantum behaviors.

Controllable transitions among phase-matching conditions in a single nonlinear crystal

Entangled photon pairs are crucial resources for quantum information processing protocols.Via the process of spontaneous parametric downconversion(SPDC),we can generate these photon pairs using bulk nonlinear crystals.Traditionally,the crystal is designed to satisfy a specific type of phase-matching condition.Here,we report controllable transitions among different types of phase matching in a single periodically poled potassium titanyl phosphate crystal.By carefully selecting pump conditions,we can satisfy different phase-matching conditions.This allows us to observe first-order Type-II,fifth-order Type-I,third-order Type-0,and fifth-order Type-II SPDCs.The temperature-dependent spectra of our source were also analyzed in detail.Finally,we discussed the possibility of observing more than nine SPDCs in this crystal.Our work not only deepens the understanding of the physics behind phase-matching conditions,but also offers the potential for a highly versatile entangled biphoton source for quantum information research.

Investigation of charge interaction between fullerene derivatives and single-walled carbon nanotubes

The charge interaction and corresponding doping effect between single-walled carbonnanotubes (SWNTs) and various fullerene derivatives, namely, C60, phenyl-C61-butyricacid methyl ester (PC61BM), methano-indenefullerene (MIF), 10,100,40,400-tetrahydrodi[1,4]methanonaphthaleno[5,6]fullerene (ICBA), 1,4-bis(dimethylphenylsilylmethyl)[60]fullerene (SIMEF-1), and dimethyl(orthoanisyl) silylmethyl(dimethylphenylsilylmethyl)[60]fullerene (SIMEF-2), are investigated. A variety of analytical techniques,including field-effect transistors (FETs) made of horizontally aligned arrays ofSWNTs, is used as a means of investigation. Data from different measurements haveto be used to obtain a concrete evaluation for the fullerene-applied SWNTs. The datacollectively points toward the conclusion that fullerenes with high molecular orbitalenergy levels, namely, MIF, SIMEF-1, SIMEF-2, and PC61BM, induce p-type doping,while fullerenes with low molecular orbital energy levels, namely, ICBA and C60,induce n-type doping on the carbon nanotubes. Nevertheless, the SWNTs retained ptypecharacteristics because n-doping induced by the fullerenes are weak compared tothe p-doping of the water and oxygen on carbon nanotubes. This means that fullerenederivatives have the ability to fine-tune the energy levels of carbon nanotubes, whichcan play a crucial role in carbon nanotube-based electronics, such as solar cells, lightemittingdevices, and FETs.