The two-site exchange with both sites detuned #
Category: 3-Local (CV; the carrier side of BACKLOG #198, the autonomous echo).
In the echo of #199 both stations carry a pointer, so both sites of the exchange are detuned by their own back-reaction: the carrier's Hamiltonian is
H = J X + Δ_A n_A + Δ_B n_B = H(Δ_B − Δ_A) + Δ_A P,
with H(Δ) the detuned exchange of DetunedExchange.lean and P the one-excitation projector.
P commutes with everything, so the flow is the detuned exchange in the difference times a
phase on the one-excitation sector:
U(t) = e^{−iΔ_A t/ħ · P} · U_{Δ_B − Δ_A}(t).
The sector phase is invisible to every observable that preserves the sector and to the rays of the
two messages, so the whole of #194's carrier algebra transfers to the two-site case with
Δ = Δ_B − Δ_A, and nothing new happens beyond the difference. What is new in this file is the
return: at the detuned round trip πħ/Ω' the carrier is back at A, as a ray, exactly.
twoDetunedH, ★twoDetunedH_eq—H = H(Δ_B − Δ_A) + Δ_A P;sectorGen,twoDetunedGen,twoDetunedGen_eq,twoDetunedGen_zero_left— atΔ_A = 0it is the detuned exchange;- ★
twoDetunedFlow J ħ Δ_A Δ_B : FieldStructuredFlow 2 2— the two-site detuned exchange is a field-structured flow on the one edge;sectorPhase,sectorPhase_eq,sectorPhase_unitary,sectorPhase_commute; ★★twoDetunedFlow_val_eq— the flow is the sector phase times the detuned exchange in the difference, byexp_add_of_commute; - ★★
arenaObs_twoDetunedFlow— every observable commuting withPreads the same along both flows, at every arena point;occB_twoDetunedFlow,occA_twoDetunedFlow,arenaObs_oneExc_twoDetunedFlow(the sector is conserved); - ★★
twoDetunedFlow_arenaFlow_msgPoint_one— on the ray of message1the two flows agree;twoDetunedFlow_msgPoint_zero— the vacuum is fixed; - ★★
twoDetuned_readout_B_one,twoDetuned_readout_A_one— the occupancies for message1are(J/Ω')² sin²(Ω't/ħ)atBand1 − (J/Ω')² sin²(Ω't/ħ)atA,Ω' = √(J² + (Δ_B − Δ_A)²/4);twoDetuned_readout_B_zero,twoDetuned_readout_A_zero— both vanish for message0; detunedRoundTrip—πħ/Ω' = 2 × detunedHopTime; ★★★detunedFlow_return,twoDetuned_return— at the detuned round trip the carrier is back atAas a ray, for the detuned exchange and for the two-site flow;twoDetuned_return_occA,twoDetuned_return_occB— withn_A = 1,n_B = 0there;occHistA,occHistA_eq,continuous_occHistA_prod,occAccumA,occAccumA_eq,hasDerivAt_occAccumA— the occupancy history ofAand its integral, in terms of the detuned exchange'soccHist/occAccum, continuous jointly in the ray and both detunings — what the pointer atAin #199 integrates;continuous_twoDetunedFlow_prod.
Honest scope #
- Nothing here is a record; the pointers that produce
Δ_A,Δ_Band read the occupancies are #199's. This file is the carrier. Δ_A,Δ_Bare real parameters; in #199 they are functions of conserved torus angles, so the flow at fixed angles is exactly this one.J > 0is assumed where the closed form divides byΩ';ħ > 0where the round trip is computed.
References: specs/BACKLOG.md #198, #199, #194, #183; CV/DetunedExchange.lean (detunedH,
detunedFlow, detunedFlow_val_eq, occHist, occAccum), CV/SignalExchange.lean (hopX,
oneExc, occB, msgPoint), Mathlib/Analysis/Normed/Algebra/ExpUnique.lean
(exp_smul_eq_cosh_sinh).
More of the algebra of P, n_A, n_B #
P commutes with the detuned flow.
The Hamiltonian with both sites detuned #
H = J X + Δ_A n_A + Δ_B n_B.
Equations
- CSD.CV.twoDetunedH J ΔA ΔB = ↑J • CSD.CV.hopX + ↑ΔA • CSD.CV.occA + ↑ΔB • CSD.CV.occB
Instances For
★ The two-site Hamiltonian is the detuned exchange in the difference plus a sector energy:
H = H(Δ_B − Δ_A) + Δ_A P.
At Δ_A = 0 the two-site Hamiltonian is the detuned exchange.
The sector generator −(i Δ_A/ħ) P.
Equations
- CSD.CV.sectorGen ħ ΔA = -(Complex.I * ↑(ΔA / ħ)) • CSD.CV.oneExc
Instances For
The Schrödinger generator −(i/ħ) H.
Equations
- CSD.CV.twoDetunedGen J ħ ΔA ΔB = -(Complex.I * ↑(1 / ħ)) • CSD.CV.twoDetunedH J ΔA ΔB
Instances For
The generator splits as the detuned exchange's plus the sector generator.
At Δ_A = 0 the generator is the detuned exchange's.
The flow #
★ The two-site detuned exchange as a field-structured flow: the one edge (A, B) carrying
−(i/ħ)(J X + Δ_A n_A + Δ_B n_B).
Equations
Instances For
The flow is continuous jointly in both detunings and the time.
The Schrödinger equation of the two-site flow.
The sector phase #
The sector phase e^{−i Δ_A t/ħ · P}.
Equations
- CSD.CV.sectorPhase ħ ΔA t = NormedSpace.exp (t • CSD.CV.sectorGen ħ ΔA)
Instances For
e^{c P} = 1 + (e^c − 1) P.
The sector phase is unitary.
★★ The two-site flow is the sector phase times the detuned exchange in the difference.
Observables and rays agree with the detuned exchange #
★★ Every observable commuting with P reads the same along the two-site flow and the detuned
exchange in the difference, at every arena point.
The occupancy of B along the two-site flow is the detuned exchange's history.
The one-excitation sector is conserved along the two-site flow.
★★ On the ray of message 1 the two-site flow is the detuned exchange in the difference.
The vacuum is fixed: message 0 never moves.
The readouts of the two messages #
★★ The receiver's occupancy for message 1: (J/Ω')² sin²(Ω't/ħ) with
Ω' = √(J² + (Δ_B − Δ_A)²/4).
The detuned round trip: the carrier returns to A #
The detuned round trip πħ/Ω.
Equations
- CSD.CV.detunedRoundTrip J ħ Δ = Real.pi * ħ / CSD.CV.rabiFreq J Δ
Instances For
At zero detuning the detuned round trip is the round trip of #183.
At the detuned round trip the detuned flow acts on e_A as the scalar −e^{−iΔ πħ/(2Ωħ)}.
★★★ The return: at the detuned round trip the carrier is back at A, as a ray, exactly.
★★★ The return of the two-site flow: at the detuned round trip in the difference, the
carrier of message 1 is back at A as a ray.
The return repeats: every multiple of the detuned round trip returns the carrier.
The occupancy history of A #
The sender's occupancy history along the two-site flow from p.
Equations
- CSD.CV.occHistA J ħ ΔA ΔB p s = CSD.CV.arenaObs CSD.CV.occA ((CSD.CV.twoDetunedFlow J ħ ΔA ΔB).arenaFlow s p)
Instances For
The history of A is continuous jointly in the ray, both detunings and the time.
The accumulated occupancy of A ∫₀ᵗ n_A(p(s)) ds.
Equations
- CSD.CV.occAccumA J ħ ΔA ΔB p t = ∫ (s : ℝ) in 0..t, CSD.CV.occHistA J ħ ΔA ΔB p s
Instances For
The accumulated occupancy of A is continuous jointly in the ray and both detunings.
The accumulated occupancy of A along continuous ray and detuning families, in the applied form
(the uncurried statement is continuous_occAccumA_prod; unifying it against an expected type unfolds
the arena and times out, so consumers take this form).
The accumulated occupancy of B along continuous ray and detuning families, in the applied
form.
Group laws along the two-site flow, and the joint energy #
The history of A from the evolved ray is the shifted history.
★ The group law of the accumulated occupancy of A along the two-site flow.
The history of B from the ray evolved by the two-site flow is the shifted history.
★ Energy conservation on the carrier: ⟨H⟩ is constant along the two-site flow.
The energy of the two-site Hamiltonian at a ray: J⟨X⟩ + Δ_A n_A + Δ_B n_B.
★ The two-site exchange with both sites detuned, in one statement: the flow is the detuned
exchange in the difference up to the sector phase; the two messages' occupancies at both sites; the
vacuum fixed; and the return of the carrier to A at the detuned round trip.