Generalized CV Conjecture and Krylov Complexity in Two-Mode Hermitian Systems via Information Geometry
Pith reviewed 2026-05-23 07:14 UTC · model grok-4.3
The pith
Krylov complexity of a quantum state equals the volume of the Fubini-Study metric in two-mode Hermitian systems.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We conjecture that the Krylov complexity of a quantum state equals the volume of the Fubini-Study metric. We test this conjecture by constructing the wave functions for both closed and open two-mode Hermitian systems. For the closed system the wave function is the two-mode squeezed state; for the open system the second kind of Meixner polynomials generate the open two-mode squeezed state. In both cases the calculated Fubini-Study volume matches the Krylov complexity, furnishing analytic support for the generalized CV relation in this controlled setting.
What carries the argument
The conjectured equality between Krylov complexity and Fubini-Study volume, verified by explicit wave-function construction in two-mode closed and open Hermitian systems.
If this is right
- The equality holds analytically for both closed two-mode squeezed states and open two-mode states generated by Meixner polynomials.
- Operator growth in Krylov space is directly linked to the geometric properties of the quantum state.
- The framework supplies a parameter-free bridge between complexity and information geometry in Hermitian two-mode dynamics.
- The same construction can be applied to other controlled multi-mode Hermitian systems to test further instances of the relation.
Where Pith is reading between the lines
- If the equality persists, geometric volume might serve as a practical proxy for computing Krylov complexity in larger systems where direct operator growth is costly.
- The result suggests a possible route to relate Krylov complexity to other geometric invariants such as entanglement entropy in the same two-mode setting.
- Testing the conjecture on non-Hermitian or time-dependent two-mode models would clarify whether the link requires Hermiticity.
Load-bearing premise
The constructed wave functions correctly represent the dynamics of the closed and open two-mode Hermitian systems and the two quantities are computed independently.
What would settle it
Compute Krylov complexity and Fubini-Study volume independently for a three-mode Hermitian system or a different two-mode model and check whether the numerical values still coincide.
read the original abstract
We extend the CV conjecture to quantum states of two-mode Hermitian systems using the framework of information geometry. Specifically, we conjecture that the Krylov complexity of a quantum state equals the volume of the Fubini-Study metric. To test this conjecture, we construct the wave functions for both closed and open two-mode systems. For the closed system, the wave function corresponds to the well-known two-mode squeezed state, while for the open system, we employ the second kind of Meixner polynomials to generate an open two-mode squeezed state. Remarkably, in both cases, the calculated Fubini-Study volume matches the Krylov complexity, providing analytic evidence for the generalized CV relation in this controlled two-mode setting. Our results establish a direct link between operator growth in Krylov space and geometric properties of quantum states, highlighting the potential applications of this framework in quantum information and quantum optics.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript extends the CV conjecture to two-mode Hermitian systems within information geometry, conjecturing that the Krylov complexity of a quantum state equals the volume of the associated Fubini-Study metric. The conjecture is tested by explicit construction of wave functions: the standard two-mode squeezed vacuum for the closed system and a state generated via the second kind of Meixner polynomials for the open system. In both cases the authors report an exact analytic match between the independently computed Krylov complexity and Fubini-Study volume.
Significance. If the reported equality holds beyond the two examined cases, the work supplies a concrete geometric interpretation of operator growth that could be useful in quantum optics and quantum information. The manuscript earns credit for performing independent, parameter-free analytic calculations on standard and explicitly defined wave functions rather than fitting or circular re-use of quantities.
minor comments (2)
- A brief, self-contained reminder of the original CV conjecture (including its domain of validity) would help readers who are not already familiar with the literature.
- The abstract and introduction refer to 'the second kind of Meixner polynomials' without a short definition or reference; adding one sentence would improve accessibility.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of the manuscript, accurate summary of our results, and recommendation to accept. No major comments were raised that require point-by-point responses.
Circularity Check
No significant circularity; conjecture tested by independent computations
full rationale
The paper advances a conjecture equating Krylov complexity to Fubini-Study volume and verifies it via explicit analytic calculations on independently constructed wave functions (two-mode squeezed state for closed systems; Meixner-polynomial states for open systems). Both quantities are computed separately from the same states with no shared parameters, no redefinition of one in terms of the other, and no load-bearing self-citations that reduce the central claim to prior unverified work by the authors. The matching is presented as empirical support for the conjecture rather than a derivation that collapses by construction. This is a standard non-circular verification step.
Axiom & Free-Parameter Ledger
Reference graph
Works this paper leans on
-
[1]
can be employed to distinguish which com- ponents represent an open system and which parts rep- resent a closed system. Reference [ 58] even discusses the possibility that a Hermitian Hamiltonian could exhibit characteristics of an open system. In this letter, we will focus on the most general two- mode Hamiltonian concerning the creation and anni- hilati...
-
[2]
M. A. Nielsen, M. R. Dowling, M. Gu, and A. C. Doherty, Quantum Computation as Geometry, Science 311, 1133 (2006) , arXiv:quant-ph/0603161. 5
work page internal anchor Pith review Pith/arXiv arXiv 2006
- [3]
-
[4]
Addendum to Computational Complexity and Black Hole Horizons
L. Susskind, Computational Complexity and Black Hole Horizons, Fortsch. Phys. 64, 24 (2016) , [Addendum: Fortsch.Phys. 64, 44–48 (2016)], arXiv:1403.5695 [hep-th]
work page internal anchor Pith review Pith/arXiv arXiv 2016
-
[5]
Complexity and Shock Wave Geometries
D. Stanford and L. Susskind, Complexity and Shock Wave Geometries, Phys. Rev. D 90, 126007 (2014) , arXiv:1406.2678 [hep-th]
work page internal anchor Pith review Pith/arXiv arXiv 2014
-
[6]
J. M. Maldacena, The Large N limit of su- perconformal field theories and supergrav- ity, Adv. Theor. Math. Phys. 2, 231 (1998) , arXiv:hep-th/9711200
work page internal anchor Pith review Pith/arXiv arXiv 1998
-
[7]
M. A. Nielsen, A geometric approach to quantum cir- cuit lower bounds, Quant. Inf. Comput. 6, 213 (2006) , arXiv:quant-ph/0502070
work page internal anchor Pith review Pith/arXiv arXiv 2006
-
[8]
M. R. Dowling and M. A. Nielsen, The geometry of quan- tum computation, Quant. Inf. Comput. 8, 0861 (2008) , arXiv:quant-ph/0701004
work page internal anchor Pith review Pith/arXiv arXiv 2008
-
[9]
Towards Complexity for Quantum Field Theory States
S. Chapman, M. P. Heller, H. Marro- chio, and F. Pastawski, Toward a Defini- tion of Complexity for Quantum Field The- ory States, Phys. Rev. Lett. 120, 121602 (2018) , arXiv:1707.08582 [hep-th]
work page internal anchor Pith review Pith/arXiv arXiv 2018
-
[10]
E. Rabinovici, A. S´ anchez-Garrido, R. Shir, and J. Son- ner, Operator complexity: a journey to the edge of Krylov space, JHEP 06, 062 , arXiv:2009.01862 [hep-th]
- [11]
-
[12]
D. Patramanis, Probing the entanglement of operator growth, PTEP 2022, 063A01 (2022) , arXiv:2111.03424 [hep-th]
-
[13]
Cao, A statistical mechanism for operator growth , J
X. Cao, A statistical mechanism for oper- ator growth, J. Phys. A 54, 144001 (2021) , arXiv:2012.06544 [cond-mat.stat-mech]
- [14]
-
[15]
R. Heveling, J. Wang, and J. Gemmer, Nu- merically probing the universal operator growth hypothesis, Phys. Rev. E 106, 014152 (2022) , arXiv:2203.00533 [cond-mat.stat-mech]
-
[16]
A. Dymarsky and M. Smolkin, Krylov complexity in con- formal field theory, Phys. Rev. D 104, L081702 (2021) , arXiv:2104.09514 [hep-th]
-
[17]
P. Caputa and S. Datta, Operator growth in 2d CFT, JHEP 12, 188 , [Erratum: JHEP 09, 113 (2022)], arXiv:2110.10519 [hep-th]
-
[18]
P. Caputa and S. Liu, Quantum complexity and topolog- ical phases of matter, Phys. Rev. B 106, 195125 (2022) , arXiv:2205.05688 [hep-th]
-
[19]
B. Bhattacharjee, X. Cao, P. Nandy, and T. Pathak, Krylov complexity in saddle-dominated scrambling, JHEP 05, 174 , arXiv:2203.03534 [quant-ph]
-
[20]
K. Adhikari and S. Choudhury, Cosmological Krylov Complexity, Fortsch. Phys. 70, 2200126 (2022) , arXiv:2203.14330 [hep-th]
- [21]
-
[22]
P.-Z. He and H.-Q. Zhang, Krylov Complex- ity in the Schr¨ odinger Field Theory, (2024), arXiv:2411.16302 [hep-th]
-
[23]
P.-Z. He and H.-Q. Zhang, Probing Krylov complex- ity in scalar field theory with general temperatures, JHEP 11, 014 , arXiv:2407.02756 [hep-th]
-
[24]
K. Hashimoto, K. Murata, N. Tanahashi, and R. Watan- abe, Krylov complexity and chaos in quantum mechanics, JHEP 11, 040 , arXiv:2305.16669 [hep-th]
- [25]
- [26]
-
[27]
B. Bhattacharjee, P. Nandy, and T. Pathak, Operator dynamics in Lindbladian SYK: a Krylov complexity per- spective, JHEP 01, 094 , arXiv:2311.00753 [quant-ph]
-
[28]
K. Adhikari, S. Choudhury, and A. Roy, Krylov Complexity in Quantum Field Theory, Nucl. Phys. B 993, 116263 (2023) , arXiv:2204.02250 [hep-th]
-
[29]
P. Caputa, H.-S. Jeong, S. Liu, J. F. Pedraza, and L.- C. Qu, Krylov complexity of density matrix operators, JHEP 05, 337 , arXiv:2402.09522 [hep-th]
- [30]
-
[31]
R. Sasaki, Towards Verifications of Krylov Complexity, PTEP 2024, 063A01 (2024) , arXiv:2403.06391 [quant-ph]
-
[32]
P. Caputa and K. Kutak, Krylov complex- ity and gluon cascades in the high en- ergy limit, Phys. Rev. D 110, 085011 (2024) , arXiv:2404.07657 [hep-ph]
-
[33]
A. Sahu, Information Gain, Operator Spreading, and Sensitivity to Perturbations as Quantifiers of Chaos in Quantum Systems , Other thesis (2024), arXiv:2404.09464 [quant-ph]
-
[34]
B. Bhattacharjee, S. Sur, and P. Nandy, Probing quantum scars and weak ergodicity breaking through quantum complexity, Phys. Rev. B 106, 205150 (2022) , arXiv:2208.05503 [quant-ph]
- [35]
- [36]
-
[37]
B. Bhattacharjee and P. Nandy, Krylov fractality and complexity in generic random matrix ensembles, (2024), arXiv:2407.07399 [quant-ph]
-
[38]
S´ anchez-Garrido,On Krylov Complexity , Ph.D
A. S´ anchez-Garrido,On Krylov Complexity , Ph.D. thesis, U. Geneva (main) (2024), arXiv:2407.03866 [hep-th]
-
[39]
A. Chattopadhyay, V. Malvimat, and A. Mitra, Krylov complexity of deformed conformal field theories, JHEP 08, 053 , arXiv:2405.03630 [hep-th]
-
[40]
V. Balasubramanian, R. N. Das, J. Erdmenger, and Z.- Y. Xian, Chaos and integrability in triangular billiards, 6 (2024), arXiv:2407.11114 [hep-th]
-
[41]
A. Bhattacharya, R. N. Das, B. Dey, and J. Erd- menger, Spread complexity and localization in PT- symmetric systems, Phys. Rev. B 110, 064320 (2024) , arXiv:2406.03524 [hep-th]
-
[42]
V. Mohan, Krylov complexity of open quantum sys- tems: from hard spheres to black holes, JHEP 11, 222 , arXiv:2308.10945 [hep-th]
-
[43]
P.-Z. He, Revisit the relationship between spread complexity rate and radial momentum, (2024), arXiv:2411.19172 [hep-th]
-
[44]
A. Bhattacharya, P. Nandy, P. P. Nath, and H. Sahu, Operator growth and Krylov construction in dissipative open quantum systems, JHEP 12, 081 , arXiv:2207.05347 [quant-ph]
-
[45]
A. Bhattacharya, P. Nandy, P. P. Nath, and H. Sahu, On Krylov complexity in open systems: an approach via bi-Lanczos algorithm, JHEP 12, 066 , arXiv:2303.04175 [quant-ph]
-
[46]
P. Nandy, A. S. Matsoukas-Roubeas, P. Mart ´ ınez- Azcona, A. Dymarsky, and A. del Campo, Quantum Dynamics in Krylov Space: Methods and Applications, (2024), arXiv:2405.09628 [quant-ph]
-
[47]
E. Rabinovici, A. S´ anchez-Garrido, R. Shir, and J. Sonner, A bulk manifestation of Krylov complexity, JHEP 08, 213 , arXiv:2305.04355 [hep-th]
-
[48]
Jackiw, Lower Dimensional Gravity, Nucl
R. Jackiw, Lower Dimensional Gravity, Nucl. Phys. B 252, 343 (1985)
work page 1985
-
[49]
Teitelboim, Gravitation and Hamiltonian Structure in Two Space-Time Dimensions, Phys
C. Teitelboim, Gravitation and Hamiltonian Structure in Two Space-Time Dimensions, Phys. Lett. B 126, 41 (1983)
work page 1983
- [50]
-
[51]
F. Nielsen, An elementary introduction to informa- tion geometry, arXiv e-prints , arXiv:1808.08271 (2018) , arXiv:1808.08271 [cs.LG]
- [52]
-
[53]
K.-H. Zhai and L.-H. Liu, Krylov Complexity in early universe, (2024), arXiv:2411.18405 [hep-th]
-
[54]
V. Viswanath and G. M¨ uller,The recursion method: ap- plication to many body dynamics , Vol. 23 (Springer Sci- ence & Business Media, 1994)
work page 1994
-
[55]
G. Hetyei, Meixner polynomials of the second kind and quantum algebras representing su(1, 1), Proceedings of the Royal Society A: Mathematical, Physical and Engineering
-
[56]
D. E. Parker, X. Cao, A. Avdoshkin, T. Scaffidi, and E. Altman, A universal operator growth hypothesis, Physical Review X 9, 10.1103/physrevx.9.041017 (2019)
-
[57]
B. Bhattacharjee, X. Cao, P. Nandy, and T. Pathak, Operator growth in open quantum systems: lessons from the dissipative SYK, JHEP 03, 054 , arXiv:2212.06180 [quant-ph]
- [58]
-
[59]
T. Li and L.-H. Liu, Inflationary Krylov complexity, JHEP 04, 123 , arXiv:2401.09307 [hep-th]
-
[60]
T. Li and L.-H. Liu, Krylov complexity of thermal state in early universe, (2024), arXiv:2408.03293 [hep-th]
-
[61]
T. Li and L.-H. Liu, Inflationary complexity of thermal state, (2024), arXiv:2405.01433 [hep-th]
- [62]
-
[63]
Xu, On Chord Dynamics and Complexity Growth in Double-Scaled SYK, (2024), arXiv:2411.04251 [hep-th]
J. Xu, On Chord Dynamics and Complexity Growth in Double-Scaled SYK, (2024), arXiv:2411.04251 [hep-th] . The calculation of the metric ds2 within the open system The two-mode squeezed state within the open system is written as |z⟩ = sech r 1 + u2 tanh r ∞∑ n=0 |1 − u2 1| n 2 ( − e2iφ tanh r 1 + u2 tanh r ) n |n⃗k; n−⃗k⟩. (18) Next, we calculate the inner ...
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.