**Invited Speakers**

Below is this list of invited speakers for QCMC 2018. Each invited speaker will give a 25 minute talk and will be allowed 5 minutes for questions.

- Barsotti, Lisa (MIT, USA)
- Chen, Yanbei (CalTech)
- Croke, Sarah (University of Glasgow, Scotland)
- Curty, Marcos (University of Vigo, Spain)
- Demkowicz-Dobrzański, Rafał (University of Warsaw):
**The Great Unified Theory of Quantum Metrology**—*A general model of unitary parameter estimation in presence of Markovian noise is considered, where the parameter to be estimated is associated with the Hamiltonian part of the dynamics. In absence of noise, unitary parameter can be estimated with precision scaling as 1/T, where T is the total probing time. A simple algebraic condition involving solely the operators appearing in the quantum Master equation, decides whether 1/T or 1/\sqrt{T} scaling of precision is achievable using the most general adaptive quantum estimation strategies.* - Dressel, Justin (Chapman University, USA)
- Englund, Dirk (MIT, USA)
- Fuentes, Ivette (University of Vienna, Austria)
- Giovannetti, Vittorio (Scuola Normale Superiore, Pisa, Italy)
- Heurs, Michèle (Max Planck Institute):
**Quantum noise reduction schemes for interferometric gravitational wave detection***"The first direct detection of gravitational waves from a binary black hole merger in September 2015 heralded the start of gravitational wave astronomy. Five detections later, the first detection of a merger of two neutron stars has provided multi-messenger astronomy with a new observation method. This is only the start of this exciting new era - for statistically meaningful gravitational wave astronomy it is imperative to continually improve detector sensitivity and hence increase the detection rate.*

The current second generation of interferometric gravitational detectors will be quantum limited over most of their detection band (for Advanced LIGO this will be for all frequencies above 12 Hz [S. Hild, Class. Quant. Grav. 29 (2012)]) as soon as their design sensitivity is reached. At first glance this quantum limit might appear fundamental in nature. However, different approaches exist to increase gravitational wave detector sensitivity beyond the quantum frontier, or even to surpass the standard quantum limit of interferometry (the squareroot of the quadratic sum of quantum shot noise and quantum radiation pressure noise in the interferometer, with the laser power as parameter).

I will talk about the standard quantum limit in interferometric gravitational wave detectors and exemplify methods to surpass it. In particular I will explain the principle behind Coherent Quantum Noise Cancellation [Tsang and Caves, Phys. Rev. Lett 105, 123601 (2010); and Wimmer et al., Phys. Rev. A. 89(5) 053836 (2014)], an all-optical radiation pressure noise cancellation scheme based on destructive interference with an anti-noise process, which is described by the same math as effective negative mass noise cancellation schemes in (hybrid) atomic systems [Møller, Nature 547, 191-195 (2017)]." - Howell, John (Hebrew University of Jerusalem, Israel)
- Jennewein, Thomas (University of Waterloo, Canada)
- Jiang, Liang (Yale University, USA):
**Quantum control and error correction with superconducting circuits**—*We have developed an efficient quantum control scheme that allows for arbitrary quantum processes on a cavity mode using strongly dispersive qubit-cavity interaction and time-dependent drives. In addition, we have discovered a new class of bosonic quantum error correcting codes, which can correct both cavity loss and dephasing errors. Our control scheme can readily be implemented using circuit QED systems and extended for quantum error correction to protect information encoded in bosonic codes. Moreover, engineered dissipation can also implement holonomic quantum computation using superconducting circuits.* - Klempt, Carsten (Leibnitz University, Germany)
- Kok, Pieter (University of Sheffield, UK):
**Optimal Quantum Imaging of Distant Black Bodies**—*The measurement of an object’s spatial configuration is important in many disciplines, from astronomy to engineering. We present the quantum optimal estimator for the spatial configuration of a distant body based on the black body radiation received in the far-field—this can be considered a form of reconstructive imaging. In doing so we must deal with multi-parameter quantum estimation of incompatible observables, a problem that is thus far not very well understood. We compare our optimal observables to the two mode analogue of lensed imaging and find that the latter is far from optimal, even when compared to measurements which are separable. To prove the optimality of the estimators we show that they minimise the cost function weighted by the quantum Fisher information—this is equivalent to maximising the average fidelity between the actual state and the estimated one.* - Lam, Ping Koy (Australia National University, Melbourne)
- Lett, Paul (NIST, Maryland, USA):
**Two-mode squeezing in interferometry and imaging**—*We have been developing a source of two-mode squeezing based on 4-wave mixing in Rb vapor. Using this source we have demonstrated a truncated version of the SU(1,1) interferometer based on nonlinear interactions. With this device we have demonstrated a 4 dB improvement over the shot-noise limit for phase measurements at low intensities. We have also been developing the source to provide squeezing at very low-frequencies and we have now made several improvements to obtain intensity-difference squeezing below 20 Hz. We hope to use this to enable direct intensity-difference imaging on a ccd camera.* - Ling, Alexander (National University of Singapore)
- Lu, Chao-Yang (USTC, China)
- Monroe, Christopher (University of Maryland, US):

Given by Norbert Linke**Quantum algorithms with trapped ions**—*Trapped ions are a promising candidate system to realize a scalable quantum computer. We present a modular quantum computing architecture comprised of a chain of 171Yb+ ions with individual Raman beam addressing and individual readout [1]. We use the transverse modes of motion in the chain to produce entangling gates between any qubit pair. This creates a fully connected system which can be configured to run any sequence of single- and two-qubit gates, making it in effect an arbitrarily programmable quantum computer that does not suffer any swap-gate overhead [2]. Recent results from different quantum algorithms on five ions will be presented, including a quantum error detection protocol that fault-tolerantly encodes a logical qubit [3], and a 3-qubit Grover search where we implemented a complete oracle data base [4]. I will also discuss current work and ideas to scale up this architecture.* - Oberthaler, Markus (University of Heidelberg, Germany):

Given by Helmut Strobel**Genuine multipartite entanglement and Einstein-Podolsky-Rosen steering of atomic clouds**—*To generate a squeezed vacuum state, we use spin mixing in a tightly confined Bose-Einstein condensate of 87Rb in a single spatial mode. We show experimentally that the corresponding particle entanglement can be spatially distributed by self-similar expansion of the atomic cloud in a waveguide potential. Spatially resolved spin read-out is used to reveal Einstein-Podolsky-Rosen (EPR) steering between distinct parts of the expanded cloud. To quantify the connection between the strength of EPR steering and genuine multipartite entanglement we construct a witness, which testifies up to genuine five-partite entanglement.* - O'Brien, Jeremy (University of Bristol, UK)
- Okamoto, Ryo (Kyoto University)
- Polzik, Eugene (Niels Bohr Institute, Denmark):
**Measurement of motion in a negative mass reference frame: from nanomechanics to gravitational wave detectors**—*A continuous measurement of a position of an object imposes a random quantum back action (QBA) perturbation on its momentum. This randomness translates with time into position uncertainty, thus leading to the well known uncertainty of the measurement of motion. As a consequence, and in accordance with the Heisenberg uncertainty principle, the QBA puts a limitation—the so-called standard quantum limit—on the precision of sensing of position, velocity and force. In this talk I will first present the results of the experiment where motion of a mechanical oscillator is tracked with the precision not restricted by the QBA. This is achieved by measuring the motion in a special reference frame linked to an atomic spin system with an effective negative mass. I will then outline a proposal for employing this principle for reaching beyond the SQL precision with Gravitational Wave Detectors, such as LIGO and the Hannover 10m prototype.* - Regal, Cindy (JILA, Boulder, Colorado, US)
- Schnabel, Roman (University of Hamburg, Germany):
**Gaussian Entanglement and Quantum Key Distribution**—*Einstein-Podolsky-Rosen entangled light with Gaussian quantum statistics of a continuous-variable (CV) allows for quantum key distribution (QKD) with one-sided device independent security [1]. Furthermore, since a single measurement that is taken on Alice’s and Bob’s sites can yield many bits, CV QKD is envisioned to provide high data rates. Since CV QKD does not use conditioning on modes that contain photons, however, decoherence does strongly limit the achievable distance. Iterative (multistep) entanglement distillation protocols have long been proposed to overcome decoherence, but their probabilistic nature makes them inefficient since the success probability decays exponentially with the number of steps unless quantum memories are used. This talk reports on our proof-of-principle experiment that demonstrated efficient iterative entanglement distillation without quantum memories [2]. An outlook with regard to useful real-world applications of entanglement-based CV QKD is given.* - Sørensen, Anders (Niels Bohr Institute)
- Tsang, Mankei (National University of Singapore):
**Seize the Moments: Enhancing Moment Estimation for Subdiffraction Incoherent Imaging**—*I propose a far-field imaging method called spatial-mode demultiplexing (SPADE) to estimate the moments of an arbitrary subdiffraction object. I show that the estimation errors can be lower than the Cramer-Rao bounds for direct imaging by orders of magnitude. Realizable with linear optics and photon counting, SPADE should find applications in both observational astronomy and fluorescence microscopy, such as object size and shape estimation. The quantum optimality of the method remains an open problem.* - Vladen, Vuletić (MIT, USA)
- Waks, Edo (University of Maryland, USA)
- Ye, Jun (JILA, Boulder, Colorado)