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  <id>https://mqwsw.sciencesconf.org/</id>
  <title><![CDATA[]]></title>
  <updated>2017-06-01T10:30:09+02:00</updated>
  <link rel="self" href="https://mqwsw.sciencesconf.org/" hreflang="en"/>
  <subtitle><![CDATA[]]></subtitle>
  <logo>https://mqwsw.sciencesconf.org//img/portal/sciencesconf.nb.png</logo>
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  <entry>
    <id>2138</id>
    <title><![CDATA[Alessandro Tosini (The Hubbard Fermionic quantum walk, Università di Pavia)]]></title>
    <updated>2017-05-30T09:12:31+02:00</updated>
    <link rel="alternate" href="https://mqwsw.sciencesconf.org/"/>
    <summary><![CDATA[Quantum simulators aim at gaining a deeper understanding of complex physical quantum systems. Within this perspective discrete time quantum walks offer a possible algorithmic description for relativistic quantum fields. The Dirac equation, ruling the kinematics of free massive Fermions, is settled as the small wave-vector approximation of a quantum walk evolution. We present an interacting Fermionic quantum walk that provides the quantum circuit counterpart of the Fermionic Hubbard model. The Hubbard Fermionic quantum, which consists of two Dirac quantum walks with the addition of an on-site interaction, is solved analytically via the Bethe-ansatz. The class of solutions contains both scattering states and bound states, the last ones corresponding to the two particles joined together to form a localized molecular state.]]></summary>
  </entry>
  <entry>
    <id>2084</id>
    <title><![CDATA[Pablo Arnault (Quantum walks and interaction fields, UPMC)]]></title>
    <updated>2017-05-02T10:39:22+02:00</updated>
    <link rel="alternate" href="https://mqwsw.sciencesconf.org/"/>
    <summary><![CDATA[Discrete-time quantum walks (DTQWs) model chiral transport on a lattice. They are universal building blocks of quantum algorithms, and can mimic condensed-matter phenomenology. They have been implemented with several objects and setups, such as photons in optical networks or fibers, or cold atoms in optical lattices. When DTQWs decohere, they tend to classical random walks. In the continuous limit, i.e. in the limit of weak spin-components coupling, for modes having large wavelengths and time periods with respect to the space and time steps, respectively, DTQWs reproduce a substantial branch of classical field theory (first quantization), including couplings with (synthetic) Abelian [1, 2] and non-Abelian [3] Yang-Mills gauge fields, and/or relativistic gravitational fields [4]. Several gauge invariances on the lattice have been exhibited, showing that the connexions between DTQWs and gauge theories are not a mere emergent property of the continuous limit, but exist at the discrete level. This 15-min talk will deal with the quantum simulation, with DTQWs, of the propagation of Dirac fermions in a (1+2)-dimensional curved spacetime [5]. The construction of such DTQWs will be discussed, and an application to gravitational waves will then be studied, beyond the continuum limit. Eventually, the aforementioned ongoing DTQW-based construction of lattice gauge theories will be quickly reviewed.]]></summary>
  </entry>
  <entry>
    <id>2083</id>
    <title><![CDATA[Daniel Mills (Information Theoretically Secure Hypothesis Test for Temporally Unstructured Quantum Computation, University of Edinburgh,)]]></title>
    <updated>2017-05-02T10:37:25+02:00</updated>
    <link rel="alternate" href="https://mqwsw.sciencesconf.org/"/>
    <summary><![CDATA[Quantum computers have been shown to be useful for many applications, among them the ecient simulation of quantum systems. It may, however, be some time before a large scale universal quantum computer is built. In the meantime, several intermediate, non-universal models of quantum computation, have been developed and may prove easier to implement. The Instantaneous Quantum Poly-time (IQP) machine is one such non- universal model with signicant practical advantages. In spite of the fact that IQP uses only commuting gates, it is believed to remain hard to classically simulate. Hence, providing evidence that a machine can perform hard IQP computations would be a proof of its quantum supremacy. A hypothesis test that can be passed only by devices capable of eciently simulating IQP machines provides the aforementioned evidence. While previous work builds such a hypothesis test assuming some conjectures on computational complexity, in the present work we are able to use tools from blind quantum computing to develop an information-theoretically secure hypothesis test. To do so, we develop an implementation of an IQP computation in Measure- ment Based Quantum Computing (MBQC). This allows us to derive a blind delegated protocol for IQP computations that keeps the details of the computa- tion hidden from the device performing it. We can prove information-theoretic security of this protocol in a composable framework. This requires that we empower the client with minimal quantum capabilities such as those required in standard Quantum Key Distribution schemes. Finally, we develop our own hypothesis test for quantum supremacy, which a limited quantum client can run on an untrusted Server.]]></summary>
  </entry>
  <entry>
    <id>2081</id>
    <title><![CDATA[Sofyan Iblisdir (Low depth quantum circuits for Ising models, Universidad Complutense de Madrid)]]></title>
    <updated>2017-05-02T10:34:26+02:00</updated>
    <link rel="alternate" href="https://mqwsw.sciencesconf.org/"/>
    <summary><![CDATA[The Ising model has proven ubiquitous in combinatorial/multiparticle problems. Its study connects to issues as diverse as (anti-) ferromagnetism, satisfiability problems, or the construction of non-trivial link invariants. In this talk, we will introduce a scheme for the detection of partition functions of the Ising model at complex temperature. In the context of ordered qubit registers, this scheme finds a natural translation in terms of global operations and single measurements on the edge of the arrays. Interestingly, the kind of state preparations and measurements involved can in principle be made "instantaneous", i.e. independent of the system size or the parameters being simulated. Through appropriate Wick rotations, estimates for real temperature partition functions can be deduced. Bounds on the estimation error, valid with high confidence are provided through a central-limit theorem. We will also show how the scheme allows to evaluate some link invariants.]]></summary>
  </entry>
  <entry>
    <id>2080</id>
    <title><![CDATA[Simone Felicetti, (Superradiant phase transition of the two-photon Dicke model, LMPQ)]]></title>
    <updated>2017-05-02T10:33:24+02:00</updated>
    <link rel="alternate" href="https://mqwsw.sciencesconf.org/"/>
    <summary><![CDATA[Analog quantum simulation schemes allow to implement spin-boson models where two-photon couplings are the dominating terms of light-matter interaction. In this case, when the coupling strength becomes comparable with the characteristic frequencies, a spectral collapse can take place, i.e. the discrete system spectrum can collapse into a continuous band. We analyzed the many-body limit of the two-photon Dicke model, which describes the interaction of a chain of qubits with a single bosonic mode. We find that there exists a parameter regime where two-photon interactions induce a superradiant phase transition, before the spectral collapse occurs. We characterize the transition by analyzing the low-energy spectrum of the system, and we compare the critical behavior with the one-photon case.]]></summary>
  </entry>
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