One of the outstanding challenges to information processing is the eloquent suppression of energy consumption in the execution of logic operations. The Landauer principle sets an energy constraint in deletion of a classical bit of information. Although some attempts have been made to experimentally approach the fundamental limit restricted by this principle, exploring the Landauer principle in a purely quantum mechanical fashion is still an open question. Employing a trapped ultracold ion, we experimentally demonstrate a quantum version of the Landauer principle, i.e., an equality associated with the energy cost of information erasure in conjunction with the entropy change of the associated quantized environment. Our experimental investigation substantiates an intimate link between information thermodynamics and quantum candidate systems for information processing.

Most nonequilibrium processes in thermodynamics are quantified only by inequalities; however, the Jarzynski relation presents a remarkably simple and general equality relating nonequilibrium quantities with the equilibrium free energy, and this equality holds in both the classical and quantum regimes. We report a single-spin test and confirmation of the Jarzynski relation in the quantum regime using a single ultracold ^{40}Ca^{+} ion trapped in a harmonic potential, based on a general information-theoretic equality for a temporal evolution of the system sandwiched between two projective measurements. By considering both initially pure and mixed states, respectively, we verify, in an exact and fundamental fashion, the nonequilibrium quantum thermodynamics relevant to the mutual information and Jarzynski equality.

Many-body interactions and correlations in atomic ensembles are fundamental in understanding many-body effects such as collective and emergent phenomena and also play an important role in various atom-based applications. Optical two-dimensional coherent spectroscopy (2DCS) provides a powerful tool to measure many-body interactions and correlations. Here, we present the study of many-body dipole–dipole interactions and correlations in potassium and rubidium atomic vapors by using double-quantum and multi-quantum 2DCS. The results show that double-quantum 2DCS provides sensitive and background-free detection of weak dipole–dipole interaction between atoms with a mean separation up to about 16 μm, and multi-quantum 2DCS can excite and detect multi-atom states (Dicke states) with up to eight correlated atoms. The technique of optical 2DCS can provide a new approach to study many-body physics in atomic ensembles and can be potentially implemented to measure many-body effects in cold atoms and other atomic/molecular systems.

We report a novel, to the best of our knowledge, double-quantum–zero-quantum two-dimensional coherent spectroscopy (2DCS) that allows direct detection of the quantum coherence between multiparticle collective states. Through correlating the double-quantum coherence and the zero-quantum coherence, signatures for coherence between collective states can be well isolated as side peaks and readily identified in the 2D spectrum. The experiment is implemented in a vapor of rubidium atoms in a collinear 2DCS setup. Good agreement with a theoretical simulation using density matrix confirms the essential role of the interatomic correlation effect in generating the side peak signals. This 2D spectrum technique paves a new avenue for studying the coherent coupling of highly excited states and many-body properties.

Giant reed is known as one of the most important energy plants as a consequence of its huge dry biomass production. It can be used for bioenergy or biopolymer production. Thus, it can replace maize and reduce the production cost of biomass and electricity. Giant reed and its products have different uses in industry. The use of giant reed as a raw material to obtain cellulose past for the production of rayon viscose and paper. Thanks to the flexible and strong of the material, giant reed can be used in the manufacture of fishing rods, brass musical instruments, canes and construction supplies. One of the most important characteristics of giant reed is that it shows strong growth capability in different soils with wide ranges of pH, salinity and high heavy metal contents and can be used for ecological remediation. Giant reed was able not only to decontaminate polluted soils with heavy metals, but also to purify the wastewater and decrease the pH and make red mud safer. Here, we review the available evidence regarding the utilization of giant reed in the field of phytoremediation and discuss the potential application of giant reed combined with advanced remediation technologies in ecological remediation.

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