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Projective Hilbert space

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1123: 906: 442: 962: 598: 839: 60: 398: 368: 242: 645: 562: 506: 262: 793: 213: 999: 141: 618: 486: 466: 345: 164: 702: 542: 760: 729: 673: 184: 86: 296: 115: 739:. Convex linear combinations of rays naturally give rise to density matrix which (still in case of an irreducible representation) correspond to mixed states. 847: 1256:
Cirelli, R; Lanzavecchia, P; Mania, A (1983). "Normal pure states of the von Neumann algebra of bounded operators as Kahler manifold".
1246: 1125:. In quantum theory, it describes how to make states of the composite system from states of its constituents. It is only an 1349: 407: 933: 992:
is an embedding of the Cartesian product of two projective spaces into the projective space associated to the
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As such, the projectivization of, e.g., two-dimensional complex Hilbert space (the space describing one
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Kong, Otto C. W.; Liu, Wei-Yin (2021). "Noncommutative Coordinate Picture of the Quantum Phase Space".
732: 1153: 813: 34: 377: 1148: 800: 445: 350: 400:. The Born rule demands that if the system is physical and measurable, its wave function has unit 1368: 928: 917: 218: 1118:{\displaystyle \mathbf {P} (H)\times \mathbf {P} (H')\to \mathbf {P} (H\otimes H'),(,)\mapsto } 630: 547: 491: 247: 765: 192: 1219:
Ashtekar, Abhay; Schilling, Troy A. (1999). "Geometrical Formulation of Quantum Mechanics".
120: 1312: 1265: 1135: 603: 471: 451: 330: 149: 144: 678: 518: 8: 1130: 796: 401: 1316: 1269: 1328: 1302: 1224: 745: 714: 658: 169: 71: 1277: 675:). No measurement can recover the phase of a ray; it is not observable. One says that 275: 94: 1345: 1281: 1242: 985: 804: 321: 89: 21: 1332: 272:, applied to a complex Hilbert space. In quantum mechanics, the equivalence classes 1320: 1273: 1234: 1158: 269: 913: 1238: 1324: 993: 973: 969: 509: 63: 1362: 1285: 989: 808: 325: 66: 965: 621: 513: 1129:, not a surjection; most of the tensor product space does not lie in its 705: 17: 652: 1229: 1126: 320:
The physical significance of the projective Hilbert space is that in
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for details of the projectivization construction in this case.
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of projective Hilbert spaces is not a projective space. The
448:. The unit norm constraint does not completely determine 1255: 1202: 1002: 936: 850: 816: 768: 748: 717: 681: 661: 633: 606: 570: 550: 521: 494: 474: 454: 410: 380: 353: 333: 278: 250: 221: 195: 172: 152: 123: 97: 74: 37: 1172: 795:, the Hilbert space reduces to a finite-dimensional 1184: 799:and the set of projective rays may be treated as a 735:of the algebra of observables then the rays induce 1117: 956: 900: 833: 787: 754: 723: 696: 667: 639: 612: 592: 556: 536: 500: 480: 460: 436: 392: 362: 339: 290: 256: 236: 207: 178: 158: 135: 109: 80: 54: 1218: 1360: 1344:. Providence (R.I.): American Mathematical Soc. 1258:Journal of Physics A: Mathematical and General 544:action) and retain its normalization. Such a 437:{\displaystyle \langle \psi |\psi \rangle =1} 957:{\displaystyle \mathbb {C} \mathbf {P} ^{1}} 425: 411: 316:Wigner's theorem § Rays and ray space 1306: 1228: 938: 920:, derived from the Hilbert space's norm. 876: 1339: 1292: 1190: 1178: 655:of observables and a representation on 1361: 1203:Cirelli, Lanzavecchia & Mania 1983 1342:Algebraic Curves and Riemann Surfaces 996:of the two Hilbert spaces, given by 649:quantum state (algebraic definition) 1223:. New York, NY: Springer New York. 593:{\displaystyle \lambda =e^{i\phi }} 13: 818: 647:correspond to the same state (cf. 268:This is the usual construction of 14: 1380: 1264:(16). IOP Publishing: 3829–3835. 244:for some non-zero complex number 1043: 1021: 1004: 944: 882: 852: 39: 834:{\displaystyle \mathrm {U} (n)} 444:, in which case it is called a 55:{\displaystyle \mathbf {P} (H)} 1112: 1100: 1097: 1094: 1091: 1085: 1079: 1073: 1070: 1064: 1047: 1039: 1036: 1025: 1014: 1008: 869: 856: 828: 822: 691: 685: 531: 525: 418: 393:{\displaystyle \lambda \neq 0} 285: 279: 104: 98: 49: 43: 1: 1212: 762:is finite-dimensional, i.e., 363:{\displaystyle \lambda \psi } 1161:, for the concept in general 7: 1278:10.1088/0305-4470/16/16/020 1239:10.1007/978-1-4612-1422-9_3 1142: 627:Rays that differ by such a 488:could be multiplied by any 309: 237:{\displaystyle v=\lambda w} 10: 1385: 1325:10.1016/j.cjph.2021.03.014 1295:Chinese Journal of Physics 979: 733:irreducible representation 313: 1154:Projective representation 1165: 1149:Complex projective space 801:complex projective space 640:{\displaystyle \lambda } 557:{\displaystyle \lambda } 501:{\displaystyle \lambda } 446:normalized wave function 298:are also referred to as 257:{\displaystyle \lambda } 26:projective Hilbert space 964:. This is known as the 929:complex projective line 788:{\displaystyle H=H_{n}} 208:{\displaystyle w\sim v} 20:and the foundations of 1340:Miranda, Rick (1995). 1119: 968:or, equivalently, the 958: 902: 835: 789: 756: 725: 698: 669: 641: 614: 594: 558: 538: 502: 482: 468:within the ray, since 462: 438: 394: 364: 341: 292: 258: 238: 209: 180: 160: 137: 136:{\displaystyle v\in H} 111: 82: 56: 1120: 959: 903: 836: 790: 757: 726: 699: 670: 642: 615: 613:{\displaystyle \phi } 595: 559: 539: 503: 483: 481:{\displaystyle \psi } 463: 461:{\displaystyle \psi } 439: 395: 365: 342: 340:{\displaystyle \psi } 293: 259: 239: 210: 181: 161: 159:{\displaystyle \sim } 138: 112: 83: 57: 1301:. Elsevier BV: 418. 1000: 934: 848: 814: 766: 746: 715: 697:{\displaystyle U(1)} 679: 659: 631: 604: 568: 548: 537:{\displaystyle U(1)} 519: 492: 472: 452: 408: 378: 351: 331: 276: 248: 219: 193: 170: 150: 145:equivalence relation 121: 117:of non-zero vectors 95: 72: 35: 1317:2021ChJPh..71..418K 1270:1983JPhA...16.3829C 1191:Kong & Liu 2021 918:Fubini–Study metric 797:inner product space 708:of the first kind. 370:represent the same 90:equivalence classes 1221:On Einstein's Path 1115: 954: 898: 831: 785: 752: 721: 694: 665: 637: 620:called the global 610: 590: 564:can be written as 554: 534: 498: 478: 458: 434: 390: 360: 337: 288: 254: 234: 205: 176: 156: 133: 107: 78: 52: 1248:978-1-4612-7137-6 986:Cartesian product 805:homogeneous space 755:{\displaystyle H} 724:{\displaystyle H} 668:{\displaystyle H} 179:{\displaystyle H} 81:{\displaystyle H} 22:quantum mechanics 1376: 1355: 1336: 1310: 1289: 1252: 1232: 1206: 1200: 1194: 1188: 1182: 1176: 1159:Projective space 1136:entangled states 1124: 1122: 1121: 1116: 1063: 1046: 1035: 1024: 1007: 963: 961: 960: 955: 953: 952: 947: 941: 912:which carries a 907: 905: 904: 899: 897: 896: 885: 879: 868: 867: 855: 840: 838: 837: 832: 821: 794: 792: 791: 786: 784: 783: 761: 759: 758: 753: 730: 728: 727: 722: 703: 701: 700: 695: 674: 672: 671: 666: 646: 644: 643: 638: 619: 617: 616: 611: 599: 597: 596: 591: 589: 588: 563: 561: 560: 555: 543: 541: 540: 535: 507: 505: 504: 499: 487: 485: 484: 479: 467: 465: 464: 459: 443: 441: 440: 435: 421: 399: 397: 396: 391: 369: 367: 366: 361: 346: 344: 343: 338: 297: 295: 294: 291:{\displaystyle } 289: 270:projectivization 263: 261: 260: 255: 243: 241: 240: 235: 214: 212: 211: 206: 185: 183: 182: 177: 165: 163: 162: 157: 142: 140: 139: 134: 116: 114: 113: 110:{\displaystyle } 108: 87: 85: 84: 79: 61: 59: 58: 53: 42: 1384: 1383: 1379: 1378: 1377: 1375: 1374: 1373: 1359: 1358: 1352: 1249: 1215: 1210: 1209: 1201: 1197: 1189: 1185: 1177: 1173: 1168: 1145: 1133:and represents 1056: 1042: 1028: 1020: 1003: 1001: 998: 997: 982: 948: 943: 942: 937: 935: 932: 931: 886: 881: 880: 875: 863: 859: 851: 849: 846: 845: 817: 815: 812: 811: 779: 775: 767: 764: 763: 747: 744: 743: 716: 713: 712: 680: 677: 676: 660: 657: 656: 632: 629: 628: 605: 602: 601: 581: 577: 569: 566: 565: 549: 546: 545: 520: 517: 516: 493: 490: 489: 473: 470: 469: 453: 450: 449: 417: 409: 406: 405: 379: 376: 375: 352: 349: 348: 332: 329: 328: 318: 312: 304:projective rays 277: 274: 273: 249: 246: 245: 220: 217: 216: 215:if and only if 194: 191: 190: 171: 168: 167: 151: 148: 147: 122: 119: 118: 96: 93: 92: 73: 70: 69: 38: 36: 33: 32: 12: 11: 5: 1382: 1372: 1371: 1369:Hilbert spaces 1357: 1356: 1350: 1337: 1290: 1253: 1247: 1214: 1211: 1208: 1207: 1195: 1183: 1170: 1169: 1167: 1164: 1163: 1162: 1156: 1151: 1144: 1141: 1114: 1111: 1108: 1105: 1102: 1099: 1096: 1093: 1090: 1087: 1084: 1081: 1078: 1075: 1072: 1069: 1066: 1062: 1059: 1055: 1052: 1049: 1045: 1041: 1038: 1034: 1031: 1027: 1023: 1019: 1016: 1013: 1010: 1006: 994:tensor product 981: 978: 974:Hopf fibration 970:Riemann sphere 951: 946: 940: 910: 909: 895: 892: 889: 884: 878: 874: 871: 866: 862: 858: 854: 830: 827: 824: 820: 782: 778: 774: 771: 751: 720: 693: 690: 687: 684: 664: 636: 609: 587: 584: 580: 576: 573: 553: 533: 530: 527: 524: 510:absolute value 497: 477: 457: 433: 430: 427: 424: 420: 416: 413: 389: 386: 383: 372:physical state 359: 356: 336: 326:wave functions 322:quantum theory 311: 308: 287: 284: 281: 266: 265: 253: 233: 230: 227: 224: 204: 201: 198: 175: 155: 132: 129: 126: 106: 103: 100: 88:is the set of 77: 51: 48: 45: 41: 9: 6: 4: 3: 2: 1381: 1370: 1367: 1366: 1364: 1353: 1351:0-8218-0268-2 1347: 1343: 1338: 1334: 1330: 1326: 1322: 1318: 1314: 1309: 1304: 1300: 1296: 1291: 1287: 1283: 1279: 1275: 1271: 1267: 1263: 1259: 1254: 1250: 1244: 1240: 1236: 1231: 1230:gr-qc/9706069 1226: 1222: 1217: 1216: 1204: 1199: 1192: 1187: 1181:, p. 94. 1180: 1175: 1171: 1160: 1157: 1155: 1152: 1150: 1147: 1146: 1140: 1138: 1137: 1132: 1128: 1109: 1106: 1103: 1088: 1082: 1076: 1067: 1060: 1057: 1053: 1050: 1032: 1029: 1017: 1011: 995: 991: 990:Segre mapping 987: 977: 975: 971: 967: 949: 930: 926: 921: 919: 916:, called the 915: 914:Kähler metric 893: 890: 887: 872: 864: 860: 844: 843: 842: 825: 810: 809:unitary group 806: 802: 798: 780: 776: 772: 769: 749: 740: 738: 734: 718: 709: 707: 688: 682: 662: 654: 650: 634: 625: 623: 607: 585: 582: 578: 574: 571: 551: 528: 522: 515: 511: 495: 475: 455: 447: 431: 428: 422: 414: 403: 387: 384: 381: 373: 357: 354: 334: 327: 323: 317: 307: 305: 301: 282: 271: 251: 231: 228: 225: 222: 202: 199: 196: 189: 188: 187: 173: 153: 146: 130: 127: 124: 101: 91: 75: 68: 67:Hilbert space 65: 46: 31: 27: 23: 19: 1341: 1298: 1294: 1261: 1257: 1220: 1198: 1193:, p. 9. 1186: 1179:Miranda 1995 1174: 1134: 983: 966:Bloch sphere 922: 911: 742:In the case 741: 710: 626: 514:circle group 371: 319: 303: 299: 267: 29: 25: 15: 841:. That is, 737:pure states 706:gauge group 18:mathematics 1308:1903.11962 1213:References 803:; it is a 653:C*-algebra 651:, given a 374:, for any 314:See also: 143:, for the 1286:0305-4470 1127:embedding 1107:⊗ 1098:↦ 1054:⊗ 1040:→ 1018:× 927:) is the 891:− 635:λ 608:ϕ 586:ϕ 572:λ 552:λ 496:λ 476:ψ 456:ψ 426:⟩ 423:ψ 415:ψ 412:⟨ 385:≠ 382:λ 358:ψ 355:λ 335:ψ 252:λ 229:λ 200:∼ 186:given by 154:∼ 128:∈ 30:ray space 1363:Category 1333:85543324 1143:See also 1061:′ 1033:′ 310:Overview 1313:Bibcode 1266:Bibcode 980:Product 512:1 (the 64:complex 1348:  1331:  1284:  1245:  972:. See 807:for a 731:is an 324:, the 24:, the 1329:S2CID 1303:arXiv 1225:arXiv 1166:Notes 1131:range 925:qubit 704:is a 622:phase 600:with 508:with 62:of a 1346:ISBN 1282:ISSN 1243:ISBN 984:The 402:norm 347:and 300:rays 1321:doi 1274:doi 1235:doi 711:If 302:or 166:on 28:or 16:In 1365:: 1327:. 1319:. 1311:. 1299:71 1297:. 1280:. 1272:. 1262:16 1260:. 1241:. 1233:. 1139:. 624:. 404:, 306:. 1354:. 1335:. 1323:: 1315:: 1305:: 1288:. 1276:: 1268:: 1251:. 1237:: 1227:: 1205:. 1113:] 1110:y 1104:x 1101:[ 1095:) 1092:] 1089:y 1086:[ 1083:, 1080:] 1077:x 1074:[ 1071:( 1068:, 1065:) 1058:H 1051:H 1048:( 1044:P 1037:) 1030:H 1026:( 1022:P 1015:) 1012:H 1009:( 1005:P 950:1 945:P 939:C 908:, 894:1 888:n 883:P 877:C 873:= 870:) 865:n 861:H 857:( 853:P 829:) 826:n 823:( 819:U 781:n 777:H 773:= 770:H 750:H 719:H 692:) 689:1 686:( 683:U 663:H 583:i 579:e 575:= 532:) 529:1 526:( 523:U 432:1 429:= 419:| 388:0 286:] 283:v 280:[ 264:. 232:w 226:= 223:v 203:v 197:w 174:H 131:H 125:v 105:] 102:v 99:[ 76:H 50:) 47:H 44:( 40:P

Index

mathematics
quantum mechanics
complex
Hilbert space
equivalence classes
equivalence relation
projectivization
Wigner's theorem § Rays and ray space
quantum theory
wave functions
norm
normalized wave function
absolute value
circle group
phase
quantum state (algebraic definition)
C*-algebra
gauge group
irreducible representation
pure states
inner product space
complex projective space
homogeneous space
unitary group
Kähler metric
Fubini–Study metric
qubit
complex projective line
Bloch sphere
Riemann sphere

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