Move Aside Pentacene: Diazapentacene‐Doped para‐Terphenyl, a Zero‐Field Room‐Temperature Maser with Strong Coupling for Cavity Quantum Electrodynamics

Abstract

quality-factor (Q) microwave resonator magnetically loaded with optically pumped pentacene doped in para-terphenyl (Pc:PTP) provides one route toward this goal, [1] and diamond with negatively charged nitrogen-vacancy defects (NV − diamond) has also been considered. [2] However, attaining a sufficiently high spin polarization density for strong coupling from other materials has, at room-temperature, proven elusive.Room-temperature masers (microwave amplification by stimulated emission of radiation) can be made out of either Pc:PTP or NV − diamond, [4,5] but Pc:PTP remains the sole material able to mase without any externally applied magnetic field (zero-field) at room-temperature. Unfortunately, it has a drawback in that it suffers from lag (of several microseconds) at start up; when operating in pulsed mode (e.g., providing low-noise amplification solely when required) this lag excludes applications that require a rapid response. Since masers on the benchtop remain as tantalizing prospects for achieving ultralow-noise amplification applicable to MRI in medical devices, deep space communication and for demonstrating cQED at room-temperature, [1] the discovery of other maser materials could help accelerate developments in these fields. Masers can deliver ultralow-noise amplification of microwave signals in medical imaging and deep-space communication, with recent research beingrekindled through the discovery of gain media operating at room-temperature, eschewing bulky cryogenics that hindered their use. This work shows the discovery of 6,13-diazapentacene doped in para-terphenyl (DAP:PTP) as a maser gain medium that can operate at room-temperature, without an external magnetic field. With a maser output power of −10 dBm, it is on par with pentacene-doped para-terphenyl in masing power, while possessing compelling advantages such as faster amplification startup times, being pumped by longer wavelength light at 620 nm and greater chemical stability from nitrogen groups. Furthermore, the maser bursts from DAP:PTP allow one to reach the strong coupling regime for cavity quantum electrodynamics, with a high cooperativity of 182. The optical and microwave spin dynamics of DAP:PTP are studied in order to evaluate its capabilities as a maser gain medium, where it features fast intersystem crossing and an advantageously higher triplet quantum yield. The results pave the way for the future discovery of similar maser materials and help designate them as promising candidates for quantum sensors, optoelectronic devices and the study of cavity quantum electrodynamic effects at room-temperature.

Large-Sized Nitrogen-Containing Biphenyl-Doped p-Terphenyl Crystals with Tunable Luminescence for Organic Scintillators

“…No characteristic emission peaks of doping molecules (PNZ, DHPNZ, and DAT) were observed in PNZ-PTP, DHPNZ-PTP, and DAT-PTP crystals, indicating that PNZ, DHPNZ, and DAT were mixed with only p -terphenyl and were not successfully doped into the p -terphenyl lattice. According to previously reported experimental results, DAP was doped into the p -terphenyl lattice, replacing one of the p -terphenyl molecules . The possible replacement process can be seen in Figure .…”

“…previously reported experimental results, DAP was doped into the pterphenyl lattice, replacing one of the p-terphenyl molecules. 47 The possible replacement process can be seen in Figure 3. In order to characterize crystal crystallinity and analyze crystal composition, XRD patterns of pure p-terphenyl and doped crystals are shown in Figure 4a,d.…”

N-Heteroacenes as an Organic Gain Medium for Room-Temperature Masers

“…The energy difference (Δ E ST ) between the first excited singlet state (S 1 ) and the most energetically proximal triplet state (T 2 ) was used to predict the ISC rates (κ ISC ) . Subsequent ab initio investigations revealed that guest–host interactions significantly impact the relative energies of neighboring singlet and triplet states, exemplifying some of the inherent difficulty in computationally predicting maser materials. , Nevertheless, these studies informed the discovery of 6,13-diazapentacene-doped p -terphenyl ( DAP :PTP) as an alternative maser gain media operating with a 620 nm pulsed laser . The discovery of new maser candidates is also hindered by reliance on doped crystalline materials such as p -terphenyl.…”

“… 11 , 12 Nevertheless, these studies informed the discovery of 6,13-diazapentacene-doped p -terphenyl ( DAP :PTP) as an alternative maser gain media operating with a 620 nm pulsed laser. 13 The discovery of new maser candidates is also hindered by reliance on doped crystalline materials such as p -terphenyl. Crystalline hosts are highly selective toward their compatible dopants which limits the number of candidates that can be readily explored.…”

LED-pumped room-temperature solid-state maser

“…This produced a burst of maser emission that lasted for 350 µs. The maser resulted in a peak microwave power output of -10 dBm, 10 8 times higher than the hydrogen maser, with an optical pump threshold power of around 230 W. There have been subsequent reports of room-temperature masing using pentacene [5][6][7] and similar media [8] pumped by a pulsed optical parametric oscillator in the range 570 -620 nm, itself pumped by a frequency doubled pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A room-temperature maser was also demonstrated using an ensemble of nitrogen-vacancy centres in diamond [9].…”