Kuprov: version fragment to 2.13 per IK 2026-08-30

2026-08-30T09:10:29Z

version fragment to 2.13 per IK 2026-08-30

Kuprov: sync with Spinach main f053e432: new page for the Bloch-Siegert response operator function

2026-08-30T07:49:45Z

sync with Spinach main f053e432: new page for the Bloch-Siegert response operator function

New page

{{DISPLAYTITLE:bss_ops.m}} __NOTOC__
Bloch-Siegert response operators for the optimal control module. For each control channel, returns the operator whose coefficient in every time slice of a GRAPE optimisation is the square of the physical control amplitude on that channel. The operator collects the second-order Bloch-Siegert frequency shifts of every spin in the system:

B=sum_n (gamma_n/gamma_c)^2*[1/(2*(omega_n+omega_c))
+(foreign isotopes only) 1/(2*(omega_n-omega_c))]*Lz_n

where omega_n are signed laboratory frame Zeeman frequencies from spin_system.inter.basefrqs and omega_c is the signed carrier frequency of the channel. Spins belonging to the isotope that the channel addresses receive only the never-resonant term because their resonant term is the control operator itself, which GRAPE propagates exactly. Foreign isotopes receive both terms, which sum into the Ramsey shift omega_n*omega_1n^2/(omega_n^2-omega_c^2).

Non-spin particles, that is, those whose entry in spin_system.comp.types is not 'S', are skipped. The longitudinal operators are built with [[operator.m]] and accumulated into a preallocation from [[mprealloc.m]]; the result is stored without a [[clean_up.m]] call because the matrix elements scale as inverse Zeeman frequencies and are legitimately small. The consistency check rejects a zero carrier frequency and any channel for which an omega_n+omega_c or, for foreign isotopes, an omega_n-omega_c denominator is degenerate to within one part in a million of the carrier frequency.

==Syntax==

resp_ops=bss_ops(spin_system,channels,carrier_frq)

==Parameters==

channels - cell array of isotope strings, one per
control operator, e.g. {'1H','1H'} for
an X,Y control operator pair

carrier_frq - row vector of signed carrier frequencies
(rad/s), one per control operator; for a
transmitter on resonance this is the value
of inter.basefrqs for the channel isotope

==Outputs==

resp_ops - cell array of Bloch-Siegert response ope-
rators, one per control operator, in the
formalism of the spin system provided

==See also==
[[bloch_siegert.m]], [[optimcon.m]], [[operator.m]], [[mprealloc.m]], [[Optimal control module]]

''Version 2.11, authors: [[Ilya Kuprov]]''

← Older revision		Revision as of 09:10, 30 August 2026
Line 33:		Line 33:
	[[bloch_siegert.m]], [[optimcon.m]], [[operator.m]], [[mprealloc.m]], [[Optimal control module]]		[[bloch_siegert.m]], [[optimcon.m]], [[operator.m]], [[mprealloc.m]], [[Optimal control module]]

−	''Version 2.11, authors: [[Ilya Kuprov]]''	+	''Version 2.13, authors: [[Ilya Kuprov]]''

Bss ops.m - Revision history

Kuprov: version fragment to 2.13 per IK 2026-08-30

Kuprov: sync with Spinach main f053e432: new page for the Bloch-Siegert response operator function