Quantum state estimation

534 Pages·2004·11.736 MB·English

by  Paris M. G. A, Rehacek J. (eds.)

Lecture Notes in Physics
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ˇ
Matteo Paris Jaroslav Reha´cˇek (Eds.)
Quantum State Estimation
123
Editors
MatteoParis JaroslavRˇeha´cˇek
Universita`diMilano PalackyUniversity
DipartimentodiFisica DepartmentofOptics
ViaCeloria16 17.listopadu50
20133Milano 77200Olomouc
Italy CzechRepublic
Matteo Paris Jaroslav Rˇeha´cˇek (Eds.), Quantum State Estimation, Lect. Notes Phys. 649
(Springer,BerlinHeidelberg2004),DOI10.1007/b98673
LibraryofCongressControlNumber:2004107804
ISSN0075-8450
ISBN3-540-22329-0SpringerBerlinHeidelbergNewYork
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Preface
This book is a comprehensive collection representing most of the theoretical
and experimental developments of the last decade in the field of quantum
estimation of states and operations. Though the field is fairly new, it has
alreadybeenrecognizedasanecessarytoolforresearchersinquantumoptics
andquantuminformation.Thesubjecthasafundamentalinterestofitsown,
since it concerns the experimental characterization of the quantum state,
the basic object of the quantum description of physical systems. Moreover,
quantumestimationtechniqueshavebeenreceivingattentionfortheircrucial
role in the characterization of registers at the quantum level, which itself is
a basic tool in the development of quantum information technology.
The field is now mature and a stable part of many graduate curricula,
but only a few review papers have been published in recent years, and no
comprehensive volume with theoretical and experimental contributions has
ever appeared. We anticipate readers in the areas of fundamental quantum
mechanics,quantumandnonlinearoptics,quantuminformationtheory,com-
munication engineering, imaging and pattern recognition.
As editors, we wish to thank Berge Englert for encouragement and sup-
port,andalltheauthorsfortheircontributions,whichwilladvanceboththe
specific field and the general appreciation of it. Their efforts and the signif-
icant time they spent preparing the chapters are much appreciated. We are
also grateful to Janine O’Guinn of the University of Oregon for her excel-
lent work in copy-editing the volume. Finally, let us acknowledge support
from EC project IST-2000-29681, and Czech Ministry of Education project
LN00A015.
Milano and Olomouc, Matteo G A Paris
April 2004 Jaroslav Rˇeha´cˇek

Contents
1 Introduction
Matteo G.A. Paris, Jaroslav Rˇeh´aˇcek.............................. 1
Part I Quantum Estimation
2 Quantum Tomographic Methods
Giacomo Mauro D’Ariano, Matteo G.A. Paris,
Massimiliano F. Sacchi .......................................... 7
2.1 Introduction ............................................... 7
2.2 Wigner Functions .......................................... 10
2.3 Elements of Detection Theory................................ 12
2.4 General Tomographic Method................................ 20
2.5 Multimode Homodyne Tomography........................... 39
2.6 Maximum-Likelihood Method in Quantum Estimation .......... 46
3 Maximum-Likelihood Methods in Quantum Mechanics
Zdenˇek Hradil, Jaroslav Rˇeh´aˇcek, Jarom´ır Fiura´ˇsek, Miroslav Jeˇzek ... 59
3.1 Introduction ............................................... 59
3.2 Overview of Quantum-State Reconstruction Techniques ......... 61
3.3 ML Quantum-State Estimation .............................. 66
3.4 Estimation Errors and Fisher Information ..................... 80
3.5 Estimation of Quantum Processes ............................ 85
3.6 Estimation of Quantum Measurements ........................ 95
3.7 Discrimination Between Quantum States ...................... 100
4 Qubit Quantum State Tomography
Joseph B. Altepeter, Daniel F.V. James, Paul G. Kwiat ............. 113
4.1 State Representation........................................ 114
4.2 Exact Tomography ......................................... 125
4.3 Real Tomography:
Errors and the Maximum Likelihood Technique ................ 134
4.4 Error Analysis ............................................. 141
VIII Contents
5 Unknown Quantum States and Operations,
a Bayesian View
Christopher A. Fuchs, Ru¨diger Schack ............................. 147
5.1 Introduction ............................................... 147
5.2 The Classical de Finetti Theorem ............................ 154
5.3 The Quantum de Finetti Representation ...................... 158
5.4 Proof of the Quantum de Finetti Theorem..................... 163
5.5 Intermezzo ................................................ 170
5.6 Subjectivity of Quantum Operations.......................... 171
5.7 Quantum Process Tomography............................... 172
5.8 The Process-Tomography Theorem ........................... 173
5.9 Proof of the Process-Tomography Theorem .................... 175
5.10 Concluding Remarks........................................ 182
6 Quantum Tomography from Incomplete Data
via MaxEnt Principle
Vladim´ır Buˇzek ................................................. 189
6.1 Modest Question ........................................... 189
6.2 Complete Observation Level ................................. 190
6.3 Maxent Principle and Observation Levels...................... 197
6.4 Numerical Implementation................................... 203
6.5 Reconstruction of Motional States of Neutral Atoms ............ 211
6.6 Direct Measurement of Wigner Functions of Single Mode Fields
in Cavities................................................. 223
6.7 Conclusions................................................ 230
7 Experimental Quantum State Tomography
of Optical Fields and Ultrafast Statistical Sampling
Michael G. Raymer, Mark Beck................................... 235
7.1 Introduction ............................................... 235
7.2 Balanced Homodyne Detection of Temporal-Spatial Modes ...... 243
7.3 Quantum State Reconstruction
and Optical Mode Statistical Sampling........................ 249
7.4 Experimental Techniques .................................... 271
7.5 Array Detection............................................ 278
7.6 Conclusions................................................ 289
A Spatial-Temporal Orthogonality .............................. 289
8 Characterization of Quantum Devices
Giacomo Mauro D’Ariano, Paoloplacido Lo Presti .................. 297
8.1 Quantum Operations and Quantum Measurements ............. 299
8.2 Imprinting Quantum Operations into Quantum States .......... 307
8.3 Homodyne Tomography of Channels and POVM’s .............. 319
Contents IX
9 Quantum Operations on Qubits
and Their Characterization
Francesco De Martini, Marco Ricci, Fabio Sciarrino................. 333
9.1 Introduction ............................................... 333
9.2 Quantum-Injected Optical Parametric Amplification ............ 336
9.3 Realization of an “All Optical” Schro¨dinger-Cat................ 341
9.4 Universal Optimal Quantum Cloning Machine
and U-NOT Gate .......................................... 346
9.5 More on Contextuality and Universality ....................... 351
9.6 Teleportation Scheme Implementing
the Universal Optimal Quantum Cloning Machine
and the Universal NOT Gate ................................ 354
9.7 Quantum Entanglement and Tomographic Analysis
of Quantum Operations ..................................... 361
10 Maximum-Likelihood Estimation
in Experimental Quantum Physics
Gerald Badurek, Zdenˇek Hradil, Alexander Lvovsky,
Gabriel Molina-Teriza, Helmut Rauch, Jaroslav Rˇeh´aˇcek,
Alipasha Vaziri, Michael Zawisky ................................. 373
10.1 Introduction ............................................... 373
10.2 Maximum-Likelihood Phase Estimation ....................... 374
10.3 ML Neutron Absorption Tomography ......................... 382
10.4 ML Neutron Phase Tomography.............................. 391
10.5 Maximum-Likelihood Characterization of Photonic Qutrits ...... 399
10.6 Maximum-Likelihood Quantum Homodyne Tomography......... 406
Part II Quantum Decision
11 Discrimination of Quantum States
J´anos A. Bergou, Ulrike Herzog, Mark Hillery ...................... 417
11.1 Introduction ............................................... 417
11.2 Unambiguous Discrimination ................................ 419
11.3 State Discrimination with Minimum Error..................... 440
11.4 Discriminating Multiparticle States ........................... 459
11.5 Outlook................................................... 462
12 Quantum States: Discrimination
and Classical Information Transmission.
A Review of Experimental Progress
Anthony Chefles ................................................ 467
12.1 Introduction ............................................... 467
12.2 Minimum Error Discrimination Between Two Pure States ....... 471
12.3 Generalised Measurements and POVMs ....................... 475
X Contents
12.4 Unambiguous Discrimination Between Two Pure States ......... 477
12.5 Discrimination Among Multiple States
with Minimum Error Probability
and the Accessible Information............................... 485
12.6 Accessible Information Experiments
with Symmetric Qubit Ensembles ............................ 498
12.7 Superadditivity of the Classical Capacity ...................... 503
12.8 Discussion................................................. 508
Index......................................................... 513