Related papers: Quantum Nondemolition Squeezing of a Nanomechanica…
We theoretically describe the weak measurement of a two-level system (qubit) and quantify the degree to which such a qubit measurement has a quantum non-demolition (QND) character. The qubit is coupled to a harmonic oscillator which…
Cavity optomechanical (COM) sensors, enhanced by quantum squeezing or entanglement, have become powerful tools for measuring ultra-weak forces with high precision and sensitivity. However, these sensors usually rely on linear COM couplings,…
Entanglement plays a crucial role in proposals for quantum metrology, yet demonstrating quantum enhancement in sensing with sustained spin entanglement remains a challenging endeavor. Here, we combine optical pumping and continuous quantum…
While a propagating state of light can be generated with arbitrary squeezing by pumping a parametric resonator, the intra-resonator state is limited to 3 dB of squeezing. Here, we implement a reservoir engineering method to surpass this…
While quantum mechanics exquisitely describes the behavior of microscopic systems, one ongoing challenge is to explore its applicability to systems of larger size and mass. Unfortunately, quantum states of increasingly macroscopic objects…
Because of their small decay rates, nanomechanical modes enable studying strongly nonlinear phenomena for a moderately strong resonant driving. Here we study the response of a driven resonator to an additional probe field. We experimentally…
According to quantum theory the interactions between physical systems are quantized. As a direct consequence, measurement sensitivities are fundamentally limited by quantization noise, or just `quantum noise' in short. Furthermore,…
Quantum sensing explores protocols using the quantum resource of sensors to achieve highly sensitive measurement of physical quantities. The conventional schemes generally use unitary dynamics to encode quantities into sensor states. In…
Observing a physical quantity without disturbing it is a key capability for the control of individual quantum systems. Such back-action-evading or quantum-non-demolition measurements were first introduced in the 1970s in the context of…
Squeezing of collective atomic spins has been shown to improve the sensitivity of atomic clocks and magnetometers to levels significantly below the standard quantum limit. In most cases the requisite atom-atom entanglement has been…
We study the quantum measurement of a cantilever using a parametrically-coupled electromagnetic cavity which is driven at the two sidebands corresponding to the mechanical motion. This scheme, originally due to Braginsky et al. [V.…
We show that substantial quantum squeezing of mechanical motion can be achieved for micron-sized cantilever devices fabricated using available techniques. A method is also described for measuring the cantilever fluctuation magnitudes in the…
Conventional techniques for laser cooling, by coherent scattering off of internal states or through an optical cavity mode, have so far proved inefficient on mechanical oscillators heavier than a few nanograms. That is because larger…
A novel scheme to realize the whole class of quantum nondemolition (QND) measurements of a field quadrature is suggested. The setup requires linear optical components and squeezers, and allows optimal QND measurements of quadratures, which…
We study a system of two nanomechanical resonators embedded in a dc SQUID. We show that the inductively-coupled resonators can be treated as two entangled quantum memory elements with states that can be read from, or written on by employing…
We use a quantum nondemolition measurement to probe the collective pseudospin of an atomic ensemble in a high-finesse optical cavity. We analyze the backaction antisqueezing produced by the measurement process to show that our protocol…
Quantum technology promises revolutionizing applications in information processing, communications, sensing, and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains a major challenge in many…
Systems with low mechanical dissipation are extensively used in precision measurements such as gravitational wave detection, atomic force microscopy and quantum control of mechanical oscillators via opto- and electromechanics. The…
A model for the cooling properties of a nanocantilever by a free electron beam is presented for a capacitive interaction. The optimal parameters for position sensing and cooling applications are estimated from previous experimental…
We propose two measurement-based schemes to cool a nonlinear mechanical resonator down to energies close to that of its ground state. The protocols rely on projective measurements of a spin degree of freedom, which interacts with the…