The physics of information technology (Q2706548)

The author leads the Physics and Media Group at the MIT Media Lab and this book arose from his teaching at MIT.NEWLINENEWLINENEWLINEThe first chapter clarifies physical units, provides some basic information on particle physics and gives orders of magnitudes of various phenomena training the physical intuition of the reader. The second chapter introduces to probability and noise and connects these notions to statistical thermodynamics; the equipartition theorem is included. Next, one uses such tools for handling information in physical systems via the concept of entropy. This allows to deal with channel capacity and the special case of Gaussian noise is detailed. Two other sections deal with Fisher information and a relation between information and thermodynamics. Chapter five is central for what follows: It is devoted to electromagnetic fields and waves (Maxwell's theory). This leads to circuits and transmission lines (chap. six), antennas (chap. seven), optics (chap. eight), lenses and related technical developments (computed tomography, magnetic resonance imaging) (chap. nine). Further, in chapter ten one has an introduction to the physics of semiconductors and applications to the transistor. The interesting chapter seven is an exposition on light generation, detection and modulation. Various technical devices are described. Chapter twelve deals with magnetic storage. Chapter thirteen deals with measurement and coding of signals; here again standard devices and techniques are presented. Chapter fourteen is on the physics and technology of transducers.NEWLINENEWLINENEWLINEThe last chapter is one of the most original, introducing to topics which were absent in engineering curriculae only a few years ago. The basics of quantum mechanics are introduced (But one reads p. 253: ``The space of these vectors is called a Hilbert space which will be finite- or infinite-dimensional for discrete or continuous eigenvalues, respectively''; the eigenvalues of the Hamiltonian are probably meant but how about the harmonic oscillator?). Angular momentum and spin will be central quantities for quantum signal processing. The corresponding wave function for a proton in a magnetic field (the realization might also be polarization states of a photon) takes the form: \(|\psi\rangle= \alpha|0\rangle+ \beta|1\rangle\) where \(|0\rangle\) and \(|1\rangle\) are eigenstates and \(\alpha\) and \(\beta\) are scalars (two parameters), in contrast to the classical bits identified separately with \(|0\rangle\) and \(|1\rangle\). In general there will be \(2^N\) parameters for an \(N\)-bit classical register. This allows to handle more information at a time. The notion of entanglement is explained as well as its impact on cryptography and error correction (a consequence is also that quantum computers will not be robust). Circuits and issues of computation are exposed, too. In particular, a factorization problem using suitable analogs of the Fourier transform leads to polynomial-time solutions. The role of nuclear magnetic resonance in experimental implementation is emphasized.NEWLINENEWLINENEWLINEEach chapter has problems attached to it and solutions are provided at the end. This is where one finds also an extensive bibliography and a useful index.NEWLINENEWLINENEWLINEThe book is attractive for its presentation bringing together in a skillful way fundamentals of physics and technological devices. This allows to learn both domains in a pleasant way. There is no ideological prominence of the former. The author writes down in several instances his standpoint where physics is instrumentalized and he also advises to trust computations more than one's intuition in certain circumstances. This book is very recommended for teaching the basics of electrical engineering and the simultaneous breath of coverage and conciseness is quite amazing.