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A quantum gravity-gradiometer consists of two spatially separated ensembles of atoms interrogated by pulses of a common laser beam. The laser pulses cause the probability amplitudes of atomic ground-state hyperfine levels to interfere, producing two, motion-sensitive, phase shifts, which allow the measurement of the average acceleration of each ensemble,… (More)

- Ulvi Yurtsever
- 1994

For a large class of quantum states, all local (pointwise) energy conditions widely used in relativity are violated by the renormalized stress-energy tensor of a quantum field. In contrast, certain nonlocal positivity constraints on the quantum stress-energy tensor might hold quite generally, and this possibility has received considerable attention in… (More)

- Ulvi Yurtsever
- 1995

Locally, the stress-energy of quantized matter can become arbitrarily negative in a wide class of quantum states, thereby violating the classical positive-energy conditions of General Relativity without bound. Since without such constraints the theory would have no predictive power, uncovering what nonlocal constraints, if any, quantum field theory imposes… (More)

- Ulvi Yurtsever
- 1992

The mathematical formalism for linear quantum field theory on curved spacetime depends in an essential way on the assumption of global hy-perbolicity. Physically, what lie at the foundation of any formalism for quantization in curved spacetime are the canonical commutation relations, imposed on the field operators evaluated at a global Cauchy surface. In… (More)

- Ulvi Yurtsever
- Complexity
- 2000

A long sequence of tosses of a classical coin produces an apparently random bit string, but classical randomness is an illusion: the algorithmic information content of a classically-generated bit string lies almost entirely in the description of initial conditions. This letter presents a simple argument that, by contrast, a sequence of bits produced by… (More)

We discuss some mathematical aspects of the problem of inverting gravitational field data to extract the underlying mass distribution. While the forward problem of computing the gravity field from a given mass distribution is mathematically straightforward, the inverse of this forward map has some interesting features that make inversion a difficult… (More)

- Federico M. Spedalieri, Hwang Lee, Marian Florescu, Kishore T. Kapale, Ulvi Yurtsever, Jonathan P. Dowling
- 2003

We devise a new technique to enhance transmission of quantum information through linear optical quantum information processors. The idea is based on applying the Quantum Zeno effect to the process of photon absorption. By frequently monitoring the presence of the photon through a quantum non-demolition (QND) measurement the absorption is suppressed. Quantum… (More)

- Ulvi Yurtsever
- 1992

The origin of spacetime topology and generalizations of quantum field theory Abstract The research effort reported in this paper is directed, in a broad sense, towards understanding the small-scale structure of spacetime. The fundamental question that guides our discussion is " what is the physical content of spacetime topology? " In classical physics, this… (More)

- Caren Marzban, Ulvi Yurtsever
- KDMS '11
- 2011

A methodology is proposed for inferring the topology underlying point cloud data. The approach employs basic elements of Morse Theory, and is capable of producing not only a point estimate of various topological quantities (e.g., genus), but it can also assesses their sampling uncertainty in a probabilistic fashion. Several examples of point cloud data in… (More)

- Ulvi Yurtsever
- 1994

We describe an elementary proof that a manifold with the topology of the Politzer time machine does not admit a nonsingular, asymptotically flat Lorentz metric.