We demonstrate a modelocked ytterbium (Yb)-doped fiber laser that is designed to have strong pulse-shaping based on spectral filtering of a highly-chirped pulse in the cavity. This laser generates femtosecond pulses without a dispersive delay line or anomalous dispersion in the cavity. Pulses as short as 170 fs, with pulse energy up to 3 nJ, are produced.

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The ability to engineer and manipulate different varieties of quantum mechanical objects allows us to take advantage of their unique properties and create useful hybrid technologies 1 .Thus far, complex quantum states and exquisite quantum control have been demonstrated in systems ranging from trapped ions 2, 3 and solid state qubits 4,5 to superconducting microwave resonators 6,7 . Recently, there have been many efforts 8,9 to extend these demonstrations to the motion of complex, macroscopic objects. These mechanical objects have important practical applications in the fields of quantum information and metrology as quantum memories or transducers for measuring and connecting different types of quantum systems. In pursuit of such macroscopic quantum phenomena, mechanical oscillators have been interfaced with quantum devices such as optical cavities and superconducting circuits [10][11][12] . In particular, there have been a few experiments that couple motion to nonlinear quantum objects [13][14][15] such as superconducting qubits. Importantly, this opens up the possibility of creating, storing, and manipulating non-Gaussian quantum states in mechanical degrees of freedom. However, before sophisticated quantum control of mechanical motion can be achieved, we must overcome the challenge of realizing systems with long coherence times while maintaining a 1 arXiv:1703.00342v1 [quant-ph] 1 Mar 2017 sufficient interaction strength. These systems should be implemented in a simple and robust manner that allows for increasing complexity and scalability in the future. Here we experimentally demonstrate a high frequency bulk acoustic wave resonator that is strongly coupled to a superconducting qubit using piezoelectric transduction. In contrast to previous experiments with qubit-mechanical systems [13][14][15] , our device requires only simple fabrication methods, extends coherence times to many microseconds, and provides controllable access to a multitude of phonon modes. We use this system to demonstrate basic quantum operations on the coupled qubit-phonon system. Straightforward improvements to the current device will allow for advanced protocols analogous to what has been shown in optical and microwave resonators, resulting in a novel resource for implementing hybrid quantum technologies.Measuring and controlling the motion of massive objects in the quantum regime is of great interest for both technological applications and for furthering our understanding of quantum mechanics in complex systems. In some respects, the physics of phonons inside a crystal is similar to that of photons inside an electromagnetic resonator, which are routinely treated as quantum mechanical objects. However, such mechanical excitations involve the collective motion of a large number of atoms in the complex environment of a macroscopic object. Nevertheless, there has only been one demonstration of a nonlinear electromechanical system in the strong coupling limit 13 . The outstanding question is how to simultaneously achieve coherences 3 and c...

The generation and stable propagation of ultrashort optical pulses tend to be limited by accumulation of excessive nonlinear phase shifts. The limitations are particularly challenging in fiber-based devices, and as a result, short-pulse fiber lasers have lagged behind bulk solid-state lasers in performance. This article will review several new modes of pulse formation and propagation in fiber lasers. These modes exist with large normal cavity dispersion, and so are qualitatively distinct from the soliton-like processes that have been exploited effectively in modern femtosecond lasers but which are also quite limiting. Self-similar evolution can stabilize high-energy pulses in fiber lasers, and this leads to order-of-magnitude increases in performance: fiber lasers that generate 10 nJ pulses of 100 fs duration are now possible. Pulse-shaping based on spectral filtering of a phase-modulated pulse yields similar performance, from lasers that have no intracavity dispersion control. These new modes feature highly-chirped pulses in the laser cavity, and a theoretical framework offers the possibility of unifying our view of normal-dispersion femtosecond lasers. Instruments based on these new pulse-shaping mechanisms offer performance that is comparable to that of solid-state lasers but with the major practical advantages of fiber.Representative power spectrum and autocorrelation of pulse generated by a fiber laser with large normal cavity dispersion (top row). Calculated power spectrum, temporal intensity and phase, and evolution of a self-similar pulse in a laser (bottom row).