资源环境科技发展态势分析平台

Conventional information processors convert information between different physical carriers for processing, storage and transmission. It seems plausible that quantum information will also be held by different physical carriers in applications such as tests of fundamental physics, quantum enhanced sensors and quantum information processing. Quantum controlled molecules, in particular, could transduce quantum information across a wide range of quantum bit (qubit) frequencies-from a few kilohertz for transitions within the same rotational manifold(1), a few gigahertz for hyperfine transitions, a few terahertz for rotational transitions, to hundreds of terahertz for fundamental and overtone vibrational and electronic transitions-possibly all within the same molecule. Here we demonstrate entanglement between the rotational states of a (CaH+)-Ca-40 molecular ion and the internal states of a Ca-40(+) atomic ion(2). We extend methods used in quantum logic spectroscopy(1,3) for pure-state initialization, laser manipulation and state readout of the molecular ion. The quantum coherence of the Coulomb coupled motion between the atomic and molecular ions enables subsequent entangling manipulations. The qubit addressed in the molecule has a frequency of either 13.4 kilohertz(1) or 855 gigahertz(3), highlighting the versatility of molecular qubits. Our work demonstrates how molecules can transduce quantum information between qubits with different frequencies to enable hybrid quantum systems. We anticipate that our method of quantum control and measurement of molecules will find applications in quantum information science, quantum sensors, fundamental and applied physics, and controlled quantum chemistry.

Quantum entanglement is realized between rotational levels of a molecular ion with energy differences spanning several orders of magnitude and long-lived internal states of a single atomic ion.

Strongly correlated insulating Mott and generalized Wigner phases are detected in WSe2/WS2 moire superlattices, and their electrical properties and excited spin states are studied using an optical technique.

Moire superlattices can be used to engineer strongly correlated electronic states in two-dimensional van der Waals heterostructures, as recently demonstrated in the correlated insulating and superconducting states observed in magic-angle twisted-bilayer graphene and ABC trilayer graphene/boron nitride moire superlattices(1-4). Transition metal dichalcogenide moire heterostructures provide another model system for the study of correlated quantum phenomena(5) because of their strong light-matter interactions and large spin-orbit coupling. However, experimental observation of correlated insulating states in this system is challenging with traditional transport techniques. Here we report the optical detection of strongly correlated phases in semiconducting WSe2/WS2 moire superlattices. We use a sensitive optical detection technique and reveal a Mott insulator state at one hole per superlattice site and surprising insulating phases at 1/3 and 2/3 filling of the superlattice, which we assign to generalized Wigner crystallization on the underlying lattice(6-11). Furthermore, the spin-valley optical selection rules(12-14) of transition metal dichalcogenide heterostructures allow us to optically create and investigate low-energy excited spin states in the Mott insulator. We measure a very long spin relaxation lifetime of many microseconds in the Mott insulating state, orders of magnitude longer than that of charge excitations. Our studies highlight the value of using moire superlattices beyond graphene to explore correlated physics.

A synthetic approach is described, for efficiently converting non-van der Waals solids into two-dimensional van der Waals transition-metal chalcogenide layers with specific phases, enabling the high-throughput production of monolayers.

Although two-dimensional (2D) atomic layers, such as transition-metal chalcogenides, have been widely synthesized using techniques such as exfoliation(1-3) and vapour-phase growth(4,5), it is still challenging to obtain phase-controlled 2D structures(6-8). Here we demonstrate an effective synthesis strategy via the progressive transformation of non-van der Waals (non-vdW) solids to 2D vdW transition-metal chalcogenide layers with identified 2H (trigonal prismatic)/1T (octahedral) phases. The transformation, achieved by exposing non-vdW solids to chalcogen vapours, can be controlled using the enthalpies and vapour pressures of the reaction products. Heteroatom-substituted (such as yttrium and phosphorus) transition-metal chalcogenides can also be synthesized in this way, thus enabling a generic synthesis approach to engineering phase-selected 2D transition-metal chalcogenide structures with good stability at high temperatures (up to 1,373 kelvin) and achieving high-throughput production of monolayers. We anticipate that these 2D transition-metal chalcogenides will have broad applications for electronics, catalysis and energy storage.