Strong Electron-Hole Exchange in Coherently Coupled Quantum Dots

We have investigated few-body states in vertically stacked quantum dots. Due to small inter-dot tunneling rate, the coupling in our system is in a previously unexplored regime where electron-hole exchange is the dominant spin interaction. By tuning the gate bias, we are able to turn this coupling off and study a complementary regime where total electron spin is a good quantum number. The use of differential transmission allows us to obtain unambiguous signatures of the interplay between electron and hole spin interactions. Small tunnel coupling also enables us to demonstrate all-optical charge sensing, where conditional exciton energy shift in one dot identifies the charging state of the coupled partner.Comment: 10 pages, 3 figure

Observation of bosonic coalescence of photon pairs

Quantum theory predicts that two indistinguishable photons incident on a beam-splitter interferometer stick together as they exit the device (the pair emerges randomly from one port or the other). We use a special photon-number-resolving energy detector for a direct loophole-free observation of this quantum-interference phenomenon. Simultaneous measurements from two such detectors, one at each beam-splitter output port, confirm the absence of cross-coincidences.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let

Charge carrier complexes in monolayer semiconductors

The photoluminescence (PL) spectra of monolayer (1L) semiconductors feature peaks ascribed to different charge-carrier complexes. We perform diffusion quantum Monte Carlo simulations of the binding energies of these complexes and examine their response to electric and magnetic fields. We focus on quintons (charged biexcitons), since they are the largest free charge-carrier complexes in undoped and low doping transition-metal dichalcogenides (TMDs). We examine the accuracy of the Rytova-Keldysh interaction potential between charges by comparing the binding energies (BEs) of charge-carrier complexes in 1L-TMDs with results obtained using ab initio interaction potentials. Magnetic fields 8 T change BEs by ∼ 0.2 meV T − 1 , in agreement with experiments, with BE variations of different complexes being very similar. Our results will help identify charge complexes in the PL spectra of 1L semiconductors

Hyperfine Spectroscopy of Isotopically Engineered Group-IV Color Centers in Diamond

A quantum register coupled to a spin-photon interface is a key component in quantum communication and information processing. Group-IV color centers in diamond (SiV, GeV, and SnV) are promising candidates for this application, comprising an electronic spin with optical transitions coupled to a nuclear spin as the quantum register. However, the creation of a quantum register for these color centers with deterministic and strong coupling to the spin-photon interface remains challenging. Here, we make first-principles predictions of the hyperfine parameters of the group-IV color centers, which we verify experimentally with a comprehensive comparison between the spectra of spin active and spin neutral intrinsic dopant nuclei in single GeV and SnV emitters. In line with the theoretical predictions, detailed spectroscopy on large sample sizes reveals that hyperfine coupling causes a splitting of the optical transition of SnV an order of magnitude larger than the optical linewidth and provides a magnetic-field insensitive transition. This strong coupling provides access to a new regime for quantum registers in diamond color centers, opening avenues for novel spin-photon entanglement and quantum sensing schemes for these well-studied emitters

Reaching the Excitonic Limit in 2D Janus Monolayers by In Situ Deterministic Growth.

Named after the two-faced Roman god of transitions, transition metal dichalcogenide (TMD) Janus monolayers have two different chalcogen surfaces, inherently breaking the out-of-plane mirror symmetry. The broken mirror symmetry and the resulting potential gradient lead to the emergence of quantum properties such as the Rashba effect and the formation of dipolar excitons. Experimental access to these quantum properties, however, hinges on the ability to produce high-quality 2D Janus monolayers. Here, these results introduce a holistic 2D Janus synthesis technique that allows real-time monitoring of the growth process. This prototype chamber integrates in situ spectroscopy, offering fundamental insights into the structural evolution and growth kinetics, that allow the evaluation and optimization of the quality of Janus monolayers. The versatility of this method is demonstrated by synthesizing and monitoring the conversion of SWSe, SNbSe, and SMoSe Janus monolayers. Deterministic conversion and real-time data collection further aid in conversion of exfoliated TMDs to Janus monolayers and unparalleled exciton linewidth values are reached, compared to the current best standard. The results offer an insight into the process kinetics and aid in the development of new Janus monolayers with high optical quality, which is much needed to access their exotic properties

Bodily Ontology of the Soul and Health Reform: Adventist Turn In Christian Anthropology

Prodorom platonske antropologije, kršćanstvom još od 2. stoljeća počinje dominirati dualizam, nepomućen ponešto holističkijim tomizmom, a dodatno osnažen kartezijanizmom koji je kršćansku teologiju i dušu odgurnuo još dalje od tijela. Tek se šezdesetih godina 20. stoljeća teolozi počinju osvješćivati o daleko pozitivnijem i inkluzivnijem stavu Biblije prema tijelu. No, stoljeće prije toga, adventistički se pokret rađa u kondicionalizmu kakvog je iznio Hobbes u Levijatanu (XLIV). Čovjek nema dušu, on jest »živa duša« – tijelo oživljeno »dahom života« (Post 2,7). Bez tijela nema života, pa tako ni vječnog pakla. Ovome adventisti pridružuju i filozofiju zdravstvene reforme u kojoj njega tijela ima ključnu ulogu i o čemu ovisi intelektualni i duhovni napredak čovjeka, te na tom temelju grade obilnu zdravstvenu i obrazovnu praksu. Ova fizikalistička inačica kršćanske antropologije jedinstven je svjetonazorski doprinos filozofiji tijela i tema vrijedna akademske pažnje.Following the spread of Platonic anthropology, Christianity has started, already since the 2nd century A.D., to be dominated by dualism – a trend undisturbed by somewhat more holistic Thomism, and further strengthened by Cartesianism, which distanced Christian theology and soul even further away from the body. During the 1960s, theologians have become aware of the far more positive and inclusive attitude that the Bible has towards the body. Yet, a century before, the Adventist movement was born in conditionalism such as presented by Hobbes in Leviathan (XLIV). Man does not have a soul; he is a “living soul” – a body vivified by the “breath of life” (Gen 2:7). Without the body, there is no life, nor, consequentially, eternal hell. To this Adventists have also conjoined a philosophy of health reform in which the care of the body has a key role, and upon which depends man’s intellectual and spiritual wellbeing. On this foundation, they have built a rich healthcare and educational practice. This physicalist version of Christian anthropology is a unique worldview contribution to philosophy of the body and a subject worthy of academic attention