Deterministic creation of entangled atom-light Schr\"odinger-cat states

Quantum physics allows for entanglement between microscopic and macroscopic objects, described by discrete and continuous variables, respectively. As in Schr\"odinger's famous cat gedanken experiment, a box enclosing the objects can keep the entanglement alive. For applications in quantum information processing, however, it is essential to access the objects and manipulate them with suitable quantum tools. Here we reach this goal and deterministically generate entangled light-matter states by reflecting a coherent light pulse with up to four photons on average from an optical cavity containing one atom. The quantum light propagates freely and reaches a remote receiver for quantum state tomography. We produce a plethora of quantum states and observe negative-valued Wigner functions, a characteristic sign of non-classicality. As a first application, we demonstrate a quantum-logic gate between an atom and a light pulse, with the photonic qubit encoded in the phase of the light field.Comment: includes Methods and Supplementary Informatio

Survey data to identify the selection criteria used by breeders of four strains of Pakistani beetal goats

This article presents raw data from a survey conducted to identify the selection criteria of breeders raising either of four strains of Beetal goats, namely Beetal Faisalabadi, Beetal Makhi-Cheeni, Beetal Nuqri, and Beetal Rahim Yar Khan. After a pre-survey, a questionnaire was developed and a survey was conducted at four sites of the Punjab province of Pakistan: Faisalabad/Sahiwal, Bahawalpur/Bahawalnagar, Rajanpur, and Rahim Yar Khan. Each of these sites was the home tract of one strain. During the survey breeders (n = 162) were asked to rank the traits of their selection criteria based on the relative importance of those traits. Furthermore, the prevailing production system was also characterized by the breeders. For the interpretation of the results of this survey the readers are referred to Ref. [1]. The raw data set provided in this article can be extended in the future to include more strains of Beetal goats as well as other goat breeds. The selection criteria of breeders can change over time. This data set can also be used in future studies to investigate the temporal changes in the relative importance of different traits for the breeders. The factors potentially influencing those changes can also be investigated. This data set can further be utilized to design community based breeding plans tailored to the needs of the goat farming community.Open-Access-Publikationsfonds 202

Control of FEL Radiation by Tailoring the Seed Pulses

Seeded free-electron lasers (FELs) produce intense, ultrashort and fully coherent X-ray pulses. These seeded FEL pulses depend on the initial seed properties. Therefore, controlling the seed laser allows tailoring the FEL radiation for phase-sensitive experiments. In this contribution, we present detailed simulation studies to characterize the FELprocess and to predict the operation performance of seeded pulses. In addition, we show experimental data on the temporal characterization of the seeded FEL pulses performed at the sFLASH experiment in Hamburg

Operation of a seeded XUV free electron laser at DESY with high-gain harmonic generation seeding

The XUV free electron laser FLASH has been recently operated in the high-gain harmonic generation (HGHG) mode. We characterized the laser-induced energy modulation, as well as the temporal profile of the seeded FEL pulses. FEL saturation was reached for the 7th harmonic of the 266 nm seed laser

Concept for a Seeded FEL at FLASH2

The free-elec­tron laser (FEL) FLASH is a user fa­cil­ity de­liv­er­ing pho­ton pulses down to 4 nm wave­length. Re­cently, the sec­ond FEL un­du­la­tor beam­line 'FLASH2' was added to the fa­cil­ity. Op­er­at­ing in self-am­pli­fied spon­ta­neous emis­sion (SASE) mode, the ex­po­nen­tial am­pli­fi­ca­tion process is ini­ti­ated by shot noise of the elec­tron bunch re­sult­ing in pho­ton pulses of lim­ited tem­po­ral co­her­ence. In seeded FELs, the FEL process is ini­ti­ated by co­her­ent seed ra­di­a­tion, im­prov­ing the lon­gi­tu­di­nal co­her­ence of the gen­er­ated pho­ton pulses. The con­cep­tual de­sign of a pos­si­ble seed­ing op­tion for the FLASH2 beam­line en­vis­ages the in­stal­la­tion of the hard­ware needed for high-gain har­monic gen­er­a­tion (HGHG) seed­ing up­stream of the al­ready ex­ist­ing un­du­la­tor sys­tem. In this con­tri­bu­tion, we pre­sent the beam­line de­sign and nu­mer­i­cal sim­u­la­tions of the seeded FEL

Status of the sFLASH Experiment

The sFLASH experiment at the free-electron laser (FEL) FLASH1 is a setup for the investigation of external FEL seeding. Since 2015, the seeding scheme high-gain harmonic generation (HGHG) is being studied. At the end of the seeded FEL, an RF deflector enables time-resolved analysis of the seeded electron bunches while the photon pulses can be characterized using the technique of THz streaking. In this contribution, we present the current configuration of the experiment and give an overview of recent experimental results

Concept for a Seeded FEL at FLASH2

The free-electron laser (FEL) FLASH is a user facility delivering photon pulses down to 4 nm wavelength. Recently, the second FEL undulator beamline FLASH2 was added to the facility. Operating in self-amplified spontaneous emission (SASE) mode, the exponential amplification process is initiated by shot noise of the electron bunch, resulting in photon pulses of limited temporal coherence. In seeded FELs, the FEL process is initiated by coherent seed radiation, improving the longitudinal coherence of the generated photon pulses. The conceptual design of a possible seeding option for the FLASH2 beamline foresees the installation of the hardware needed for high-gain harmonic generation (HGHG) seeding upstream of the already existing undulator system. In this contribution, we present the beamline design and numerical simulations of the seeded FEL

Towards Chirp Control of XUV Free Electron Lasers

We use 267nm femtosecond laser pulses to modulate electrons of a XUV free electron laser. By changing the chirp of this laser pulses we can influence the chirp of the generated XUV FEL pulses, which are characterized by THz streaking. The emeasured effect is in agreement with simulations

Experience in Operating sFLASH With High-Gain Harmonic Generation

sFLASH, the experimental setup for external seeding of free-electron lasers (FEL) at FLASH, has been operated in the high-gain harmonic generation (HGHG) mode. A detailed characterization of the laser-induced energy modulation, as well as the temporal characterization of the seeded FEL pulses is possible by using a transverse deflecting structure and an electron spectrometer. FEL saturation was reached for the 7th harmonic of the 266 nm seed laser. In this contribution, we present the latest experimental results