Meta-Entanglement

We give a meta-logical interpretation of the entanglement mechanism of quantum space-time in terms of the sequent calculus of a quantum sub-structural logic. This meta-logical picture is based mainly on the two meta-rules cut and EPR, and on the new meta-theorem teleportation (TEL), built by the use of the above meta-rules, both performed in parallel. The proof of (TEL)-theorem fairly reproduces the protocol of quantum teleportation. In the framework of space-time entanglement, the conclusion of the (TEL)-theorem is that the entangled space-time can convey the quantum teleportation of an unknown quantum state. We also introduce two new structural rules: the Hadamard (H)-rule and the CNOT-rule, the latter being used, together with the cut, in the proof of the new theorem Entanglement (ENT).Comment: 21 pages, 5 figures, 1 Appendix. Submitted to MPL

From SU(2) gauge theory to qubits on the fuzzy sphere

We consider a classical pure SU(2) gauge theory, and make an ansatz, which separates the space-temporal degrees of freedom from the internal ones. This ansatz is gauge-invariant but not Lorentz invariant. In a limit case of the ansatz, obtained through a contraction map, and corresponding to a vacuum solution, the SU(2) gauge field reduces to an operator, which is the product of the generator of a global U(1) group times a Pauli matrix. We give a geometrical interpretation of the ansatz and of the contraction map in the framework of principal fiber bundles. Then, we identify the internal degrees of freedom of the gauge field with the non-commutative coordinates of the fuzzy sphere in the fundamental representation and obtain a one qubit state.Comment: 21 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:1104.011

Computability at the Planck scale

We consider the issue of computability at the most fundamental level of physical reality: the Planck scale. To this aim, we consider the theoretical model of a quantum computer on a non commutative space background, which is a computational model for quantum gravity. In this domain, all computable functions are the laws of physics in their most primordial form, and non computable mathematics finds no room in the physical world. Moreover, we show that a theorem that classically was considered true but non computable, at the Planck scale becomes computable but non decidable. This fact is due to the change of logic for observers in a quantum-computing universe: from standard quantum logic and classical logic, to paraconsistent logic.Comment: 9 pages, misprints corrected, LaTeX version, accepted as contributed paper at CiE 200

Spacetime at the Planck Scale: The Quantum Computer View

We assume that space-time at the Planck scale is discrete, quantised in Planck units and "qubitsed" (each pixel of Planck area encodes one qubit), that is, quantum space-time can be viewed as a quantum computer. Within this model, one finds that quantum space-time itself is entangled, and can quantum-evaluate Boolean functions which are the laws of Physics in their discrete and fundamental form.Comment: 12 pages. Shorter revised version for submission to journa

Quantum Computing Spacetime

A causal set C can describe a discrete spacetime, but this discrete spacetime is not quantum, because C is endowed with Boolean logic, as it does not allow cycles. In a quasi-ordered set Q, cycles are allowed. In this paper, we consider a subset QC of a quasi-ordered set Q, whose elements are all the cycles. In QC, which is endowed with quantum logic, each cycle of maximal outdegree N in a node, is associated with N entangled qubits. Then QC describes a quantum computing spacetime. This structure, which is non-local and non-casual, can be understood as a proto-spacetime. Micro-causality and locality can be restored in the subset U of Q whose elements are unentangled qubits which we interpret as the states of quantum spacetime. The mapping of quantum spacetime into proto-spacetime is given by the action of the XOR gate. Moreover, a mapping is possible from the Boolean causal set into U by the action of the Hadamard gate. In particular, the causal order defined on the elements of U induces the causal evolution of spin networks.Comment: 12 pages, 5 figure

The Early Universe as a Quantum Growing Network

We consider a quantum gravity register that is a particular quantum memory register which grows with time, and whose qubits are pixels of area of quantum de Sitter horizons. At each time step, the vacuum state of this quantum register grows because of the uncertainty in quantum information induced by the vacuum quantum fluctuations. The resulting virtual states, (responsible for the speed up of growth, i.e., inflation), are operated on by quantum logic gates and transformed into qubits. The model of quantum growing network (QGN) described here is exactly solvable, and (apart from its cosmological implications), can be regarded as the first attempt toward a future model for the quantum World-Wide Web. We also show that the bound on the speed of computation, the bound on clock precision, and the holographic bound, are saturated by the QGN.Comment: 17 pages, 2 figures.Contribution to the IQSA Fifth Conference, March 31 - April 5, 2001, Cesena-Cesenatico, Italy. Submitted to General Relativity and Gravitation. References adde

Emergent Consciousness: From the Early Universe to Our Mind

In a previous paper (gr-qc/9907063) we described the early inflationary universe in terms of quantum information. In this paper, we analize those results in more detail, and we stress the fact that, during inflation, the universe can be described as a superposed state of quantum registers. The self-reduction of the superposed quantum state is consistent with the Penrose's Objective Reduction (OR) model. The quantum gravity threshold is reached at the end of inflation, and corresponds to a superposed state of 10^9 quantum registers. This is also the number of superposed tubulins-qubits in our brain, which undergo the Penrose-Hameroff's Orchestrated Objective Reduction, (Orch OR), leading to a conscious event. Then, an analogy naturally arises between the very early quantum computing universe,and our mind.Comment: 17 page

Qubits and Quantum Spaces

We consider the quantum computational process as viewed by an insider observer: this is equivalent to an isomorphism between the quantum computer and a quantum space, namely the fuzzy sphere. The result is the formulation of a reversible quantum measurement scheme, with no hidden information.Comment: 5 pages, LaTeX. Contributed paper at Foundations of Quantum Information, 16-19 April 2004, Camerino, Italy. Shorter, final version for the Proceedings, submitted to a special issue of IJQ

Ultimate Internets

In a previous paper (gr-qc/0103002), the inflationary universe was described as a quantum growing network (QGN). Here, we propose our view of the QGN as the "ultimate Internet", as it saturates the quantum limits to computation. Also, we enlight some features of the QGN which are related to: i) the problem of causality at the Planck scale, ii) the quantum computational aspects of spacetime foam and decoherence, iii) the cosmological constant problem, iv) the "information loss" puzzle. The resulting picture is a self-organizing system of ultimate Internet-universes.Comment: 16 page

From su(2) gauge theory to spin 1/2 quantum mechanics

We consider a pure SU(2) gauge theory, and make an ansatz for the gauge field, which is gauge-invariant but manifestly non-Lorentz invariant. In a limit case of the ansatz, corresponding to a vacuum solution, the SU(2) gauge field reduces to a spin 1/2 observable times the generator of a global U(1). We find that the field equations written in terms of the ansatz make explicit the presence of an anomalous current which vanishes in the vacuum. This allows to interpret the components of the U(1) field as Goldstone bosons associated with the spontaneous breaking of Lorentz symmetry. Finally, we give an interpretation of the ansatz in the context of principal fiber bundles, which enlightens the geometrical aspects of the reduction of the gauge field theory to quantum mechanics.Comment: 9 page