Quantum information processors promise fast algorithms for problems inaccessible to classical computers. But since qubits are noisy and error-prone, they will depend on fault-tolerant quantum error correction (FTQEC) to compute reliably. Quantum error correction can protect against general noise if—and only if—the error in each physical qubit operation is smaller than a certain threshold. The threshold for general errors is quantified by their diamond norm. Until now, qubits have been assessed primarily by randomized benchmarking, which reports a different error rate that is not sensitive to all errors, and cannot be compared directly to diamond norm thresholds. Here we use gate set tomography to completely characterize operations on a trapped-Yb+-ion qubit and demonstrate with greater than 95% confidence that they satisfy a rigorous threshold for FTQEC (diamond norm ≤6.7 × 10−4).

We measure spin mixing of F=1 and F=2 spinor condensates of 87 Rb atoms confined in an optical trap. We determine the spin mixing time to be typically less than 600 ms and observe spin population oscillations. The equilibrium spin configuration in the F=1 manifold is measured for different magnetic fields and found to show ferromagnetic behavior for low field gradients. An F=2 condensate is created by microwave excitation from F=1 manifold, and this spin-2 condensate is observed to decay exponentially with time constant 250 ms. Despite the short lifetime in the F=2 manifold, spin mixing of the condensate is observed within 50 ms.PACS numbers: 03.75. Mn, 32.80.Pj, One of the hallmarks of Bose-Einstein condensation (BEC) in dilute atomic gases is the relatively weak and well-characterized inter-atomic interactions that allow quantitative comparison with theory. The vast majority of experimental work has involved single component systems, using magnetic traps confining just one Zeeman sub-level in the ground state hyperfine manifold. An important frontier in BEC research is the extension to multi-component systems, which provides a unique opportunity for exploring coupled, interacting quantum fluids. In particular, atomic BECs with internal spin degrees of freedom offer a new form of coherent matter with complex internal quantum structures. The first twocomponent condensate was produced utilizing two hyperfine states in 87 Rb, and remarkable phenomena such as phase separation were observed [1,2]. Sodium F=1 spinor BECs have been created by transferring spin polarized condensates into a far-off resonant optical trap to liberate the internal spin degrees of freedom. This allowed investigations of the ground state properties of Na spinor condensates, and observations of domain structures, metastability, and quantum spin tunneling [3,4,5].In this letter, we explore the spin dynamics and ground state properties of 87 Rb spinor condensates in an alloptical trap, by starting with well-characterized initial conditions in a known magnetic field. We focus on the F=1 case and confirm the predicted ferromagnetic behavior. We observe population oscillation between different spin states during the spin mixing and observe reduced magnetization fluctuations, pointing the way to future exploration of the underlying spin squeezing and spin entanglement predicted for the system [6]. We also create F=2 spinors using a microwave excitation, measure a decay of the condensate with a time constant of 250 ms. Despite the short lifetime, spin mixing of the spin-2 condensates is observed within 50 ms. Similar results are concurrently reported in Ref [7]; in that work, the emphasis is on the F=2 mixing, while here, we focus mainly on the F=1 manifold.A spinor BEC can be described by a multi-component order parameter which is invariant under gauge transformation and rotation in spin space [8,9,10]. For a spin-1 BEC, the condensate is either ferromagnetic or antiferromagnetic [8], and the corresponding ground state structure and dynamical prope...

Individual laser-cooled atoms are delivered on demand from a single atom magneto-optic trap to a high-finesse optical cavity using an atom conveyor. Strong coupling of the atom with the cavity field allows simultaneous cooling and detection of individual atoms for time scales exceeding 15 s. The single atom scatter rate is studied as a function of probe-cavity detuning and probe Rabi frequency, and the experimental results are in qualitative agreement with theoretical predictions. We demonstrate the ability to manipulate the position of a single atom relative to the cavity mode with excellent control and reproducibility.

Ultracold 87 Rb atoms are delivered into a high-finesse optical micro-cavity using a translating optical lattice trap and detected via the cavity field. The atoms are loaded into an optical lattice from a magneto-optic trap (MOT) and transported 1.5 cm into the cavity. Our cavity satisfies the strong-coupling requirements for a single intracavity atom, thus permitting real-time observation of single atoms transported into the cavity. This transport scheme enables us to vary the number of intracavity atoms from 1 to >100 corresponding to a maximum atomic cooperativity parameter of 5400, the highest value ever achieved in an atom-cavity system. When many atoms are loaded into the cavity, optical bistability is directly measured in real-time cavity transmission.Many applications in quantum information science require the coherent and reversible interaction of single photon fields with material qubits such as trapped atoms. Quantum states can be transferred between light and matter-respectively offering long range communication and long-term storage of quantum information. This important paradigm is the heart of cavity QED systems, which are largely focused on creating laboratory systems capable of reversible matter-photon dynamics at the single photon level [1]. To achieve this, a small high-finesse build-up cavity is used to tremendously enhance the electric field per photon and hence the interaction strength of a single photon with the cavity medium (e.g. atoms). For a single atom in the cavity, the interaction strength is given by the single photon Rabi frequency, 2g 0 , and coherent dynamics is achieved for g 2 0 /(κΓ) ≫ 1, where κ is the the cavity field decay rate and Γ is the atomic spontaneous emission rate.There have been spectacular recent successes in cavity QED research brought about by the merging of optical cavity systems with ultracold neutral atoms [2], including real-time observation [3,4,5] and trapping [6,7,8,9] of single atoms in optical cavities, real-time feedback control on a single atom [10], and single photon generation [11,12]. Together with the remarkable experimental work in microwave cavity QED [13] and the future prospects for cavity QED with trapped ions [14,15], the field is well-poised to contribute significantly to the development of quantum information science. Indeed, current cavity QED parameters are sufficient for existing quantum gate protocols with fidelities > 99.9% percent [16,17,18,19], and the systems are principally limited by the lack of a scalable atomic trapping system to provide adequate control over atom motional degrees of freedom.Our strategy for overcoming this limitation is to employ optical dipole trapping fields independent from the cavity and orthogonal to its axis as illustrated in Fig.

We present the design, fabrication, and experimental implementation of surface ion traps with Y-shaped junctions. The traps are designed to minimize the pseudopotential variations in the junction region at the symmetric intersection of three linear segments. We experimentally demonstrate robust linear and junction shuttling with greater than 10 6 round-trip shuttles without ion loss. By minimizing the direct line of sight between trapped ions and dielectric surfaces, negligible day-to-day and trap-to-trap variations are observed. In addition to high-fidelity single-ion shuttling, multiple-ion chains survive splitting, ion-position swapping, and recombining routines. The development of two-dimensional trapping structures is an important milestone for ion-trap quantum computing and quantum simulations. arXiv:1105.1834v1 [quant-ph]

ENCODE 3 (2012-2017) expanded production and added new types of assays 8 (Fig. 1, Extended Data Fig. 1), which revealed landscapes of RNA binding and the 3D organization of chromatin via methods such as chromatin interaction analysis by paired-end tagging (ChIA-PET) and Hi-C chromosome conformation capture. Phases 2 and 3 delivered 9,239 experiments (7,495 in human and 1,744 in mouse) in more than 500 cell types and tissues, including mapping of transcribed regions and transcript isoforms, regions of transcripts recognized by RNA-binding proteins, transcription factor binding regions, and regions that harbour specific histone modifications, open chromatin, and 3D chromatin interactions. The results of all of these experiments are available at the ENCODE portal (http://www.encodeproject.org). These efforts, combined with those of related projects and many other laboratories, have produced a greatly enhanced view of the human genome (Fig. 2), identifying 20,225 protein-coding and 37,595 noncoding genes

We have successfully demonstrated an integrated optical system for collecting the fluorescence from a trapped ion. The system, consisting of an array of transmissive, dielectric micro-optics and an optical fiber array, has been intimately incorporated into the ion-trapping chip without negatively impacting trapping performance. Epoxies, vacuum feedthrough, and optical component materials were carefully chosen so that they did not degrade the vacuum environment, and we have demonstrated light detection as well as ion trapping and shuttling behavior comparable to trapping chips without integrated optics, with no modification to the control voltages of the trapping chip.Integration of fluorescence collection optics with a microfabricated surface electrode ion trap

Efficient photon extraction from a quantum dot in a broad-band planar cavity antenna